San Francisco de Paula, Science Department.
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        • Unit 3a - Living things
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          • Monera
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          • Fungi
          • The Plant Kingdom
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      • Unit 4 - Ecosystems & Biodiversity
      • Unit 5: The systems of the Earth >
        • Unit 5a - The Geosphere and the Atmosphere
        • Unit 5b - The hydrosphere and the Biosphere
      • Unit 6: Our changing home >
        • Unit 6a: Internal Geodynamics
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    • Contents >
      • Units 1, 2 and 3 - Measuring Matters >
        • Unit 1 Physical quantities and Scientific Activity >
          • Converting Units
        • Unit 2 Matter and its Properties
        • Unit 3 Pure Substances and Mixtures >
          • Concentration and units (g/L, % mass)
      • Units 4 and 5 - Chemical Cooking >
        • Models of the Atom
        • Electronic structure of matter.
        • Periodic table (distribution of elements).
        • Chemical formulation
        • Molecular mass
        • Moles
        • Types of reactions
        • Lavoisier's law: Balancing of equations
        • Reaction rates: Factors that affect the speed of a reaction
      • Units 6, 7 and 8 - Move It! >
        • Unit 6 - Motion (URM)
        • Unit 6 - Motion (UARM)
        • Unit 7 - Forces and Mass
        • Unit 8 - Energy and Transformations
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      • How to write a lab report
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    • Yr9 Syllabus & Assessment
    • Contents >
      • Unit 1 - General organization of the human body, health and illness >
        • Human cells: levels of organisation
        • Health and types of diseases
        • Preventing diseases
        • The Immune System
        • Transplants
        • Addictive substances and associated substances
        • Complete Unit 1
      • Unit 2 - Nutrition >
        • Nutrition and nutrients
        • The Mediterranean diet
        • The anatomy and physiology of the digestive system
        • The anatomy and physiology of the circulatory system >
          • Revision quizzes
        • The anatomy and physiology of the respiratory system
        • The anatomy and physiology of the excretory system
        • Nutrition Documentaries
      • Unit 3 - Interaction and Coordination >
        • The function and anatomy of the nervous system
        • The endocrine system
      • Unit 4 - The reproductive system >
        • Anatomy and physiology of the human reproductive system.
        • Gametogenesis
        • Menstrual cycle
        • Fertilization
        • Infertility, contraception and STDs
      • Unit 5 - Genetics >
        • DNA and genetic modification
        • Cells and Inheritance
        • MORE ON MITOSIS VS MEIOSIS
        • Mendelian genetics
      • Unit 6 - Evolution >
        • Evolutionary theories
        • Evolution Simulators
      • EXTRA Unit 7 - Ecology and the environment >
        • Ecology
    • Laboratory & Tasks
  • MYP Year 10
    • Yr10 Syllabus
    • Contents >
      • Unit 0 - Formulation
      • Unit 1 - Scientific Activity
      • Unit 2 - Kinetic theory
      • The Atmosphere
      • Unit 3 - Mixtures and pures substances: Colligative properties
      • Unit 4 - The structure of matter
      • Unit 5 - Stoichiometry
      • Unit 6 - Redox Reactions
      • Unit 7 - Movement
      • Unit 8 - Forces
      • Unit 9 - Electricity
      • Unit 10 - Energy
    • Revision
    • Assessments and Lab Sessionss >
      • Assessments >
        • Criterion D - Water crisis
      • Session 1 - Paper balls
      • Sessions 2 - Properties of substances
      • Session 3 - Preparing a Schlenk tube
      • Session 4 - Gas constant
      • Session 5 - Colligative properties
      • Session 6 - Job´s method
      • Session 7 - Redox titration
      • Session 8 - UARM
      • Session 9 - Hooke´s Law
    • PISA questions
  • DP Biology SL
    • Contents >
      • Topic 1: Cell biology >
        • 1.1 Introduction to cells
        • 1.2 Ultrastructure of cells
        • 1.3 Membrane structure
        • 1.4 Membrane transport
        • 1.5 The origin of cells
        • 1.6 Cell division
      • Topic 2: Molecular biology >
        • 2.1 Molecules to metabolism
        • 2.2 Water
        • 2.3 Carbohydrates and lipids
        • 2.4 Proteins
        • 2.5 Enzymes
        • 2.6 Structure of DNA and RNA
        • 2.7 DNA replication, transcription and translation
        • 2.8 Cell respiration
        • 2.9 Photosynthesis
      • Topic 3: Genetics >
        • 3.1 Genes
        • 3.2 Chromosomes
        • 3.3 Meiosis
        • 3.4 Inheritance
        • 3.5 Genetic modification and biotechnology
      • Topic 4: Ecology >
        • 4.1 Species, communities and ecosystems
        • 4.2 Energy flow
        • 4.3 Carbon cycling
        • 4.4 Climate change
      • C: Ecology and conservation >
        • C.1 Species and communities
        • C.2 Communities and ecosystems
        • C.3 Impacts of humans on ecosystems
        • C.4 Conservation of biodiversity
      • Topic 5: Evolution and biodiversity >
        • 5.1 Evidence for evolution
        • 5.2 Natural selection
        • 5.3 Classification of biodiversity
        • 5.4 Cladistics
      • Topic 6: Human physiology >
        • 6.1 Digestion and absorption
        • 6.2 The blood system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Neurons and synapses
        • 6.6 Hormones, homeostasis and reproduction
    • Labs >
      • Statistical analysis
    • Previous to 2015 >
      • Topic 1: Statistical analysis
      • Topic 2: Cells >
        • 2.1 Cell theory
        • 2.2 Prokaryotic cells
        • 2.3 Eukaryotic cells
        • 2.4 Membranes
        • 2.5 Cell division
      • Option F: Microbes and biotechnology >
        • F1 Diversity of microbes
        • F2 Microbes and the environment
        • F3 Microbes and biotechnology
        • F4 Microbes and food production
      • Topic 5: Ecology and evolution >
        • 5.1 Communities and ecosystems
        • 5.2 The greenhouse effect
        • 5.3 Populations
        • 5.4 Evolution
        • 5.5 Classification
      • Option D: Evolution >
        • D1 Origin of life on Earth
        • D2 Species and speciation
        • D3 Human evolution
      • Topic 3: The chemistry of life >
        • 3.1 Chemical elements and water
        • 3.2 Carbohydrates, lipids and proteins
        • 3.3 DNA structure
        • 3.4 DNA replication
        • 3.5 Transcription and translation
        • 3.6 Enzymes
        • 3.7 Cell respiration
        • 3.8 Photosynthesis
        • TO DELETE
      • Topic 4: Genetics >
        • 4.1 Chromosomes, genes, alleles and mutations
        • 4.2 Meiosis
        • 4.3 Theoretical genetics
        • 4.4 Genetic engineering and biotechnology
      • Topic 6: Human health and physiology >
        • 6.1 Digestion
        • 6.2 The transport system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Nerves, hormones and homeostasis
        • 6.6 Reproduction
    • Tasks >
      • Databases
    • Documents
    • DP Biology Resources
    • Interesting links
  • Biología 12º
    • Bloque 1. Bioquímica
    • Bloque 2. Biología celular
    • Bloque 3. Genética y evolución
    • Bloque 4. Microbiología y biotecnología
    • Bloque 5. Inmunología
  • IB Biología NS
  • IB Chemistry HL
    • Contents >
      • Year 1 >
        • Topic 0 - Formulation
        • Topic 1 - Stoichiometric relationships
        • Topic 2 and 12 - Atomic structure
        • Topic 3 and 13 - Periodicity
        • Topic 4 and 14 - Chemical structure and bonding
        • Topic 5 and 15 - Energetics
        • Topic 10 and 20 - Organic chemistry
      • Year 2 >
        • Topic 6 and 16 - Chemical kinetics
        • Topic 7 and 17 - Equilibrium
        • Topic 8 and 18 - Acids and bases
        • Topic 9 and 19 - Redox processes
        • Topic 11 and 21 - Measurement and data processing
        • Option D - Medicinal chemistry
    • Lab work >
      • SFP Campus lab reports
      • Internal assessment structure
      • Internal Assessment examples
    • Nature of science
    • General revision
    • Selectividad
    • General information
    • Extended Essay
  • Other resources for students
    • Science Fair
    • Science essays >
      • How to Reference
    • Chemical formulation
    • Laboratory >
      • How to write a lab report
      • Microscopy
      • Excel for graphs and calculations >
        • Calculate the mean and SD
        • Drawing graphs
        • Add error bars to excel graphs
      • Lab videos!
    • Further Reading >
      • Women In Science
      • Infographics
    • Proyecto integrado
  • Department Home page
    • The International Baccalaureate
    • Conceptual learning
    • How will I be assessed?
    • Primary Science Club
    • Science Activities Noticeboard
  • MYP Year 6
    • Yr 6 Syllabus & Assessment
    • Contents >
      • Unit 1: Introduction to investigation >
        • How to write Lab Reports
      • Unit 2: Living things
      • Unit 3: Classification of living things
      • Unit 4: Fungi, Protists and Bacteria
      • Unit 5: Nutrition I
    • Laboratory and Tasks
  • MYP Year 7
    • Yr 7 Syllabus & Assessment
    • Contents >
      • 7º PAI en español
      • Unit 1 - What do scientists do? >
        • How to write a lab report
        • SI Units
      • Unit 2 - The Earth in the Universe
      • Unit 3: How can we study living things >
        • Unit 3a - Living things
        • Unit 3b - The Diversity of Life >
          • Monera
          • Protists
          • Fungi
          • The Plant Kingdom
          • The Animal Kingdom
      • Unit 4 - Ecosystems & Biodiversity
      • Unit 5: The systems of the Earth >
        • Unit 5a - The Geosphere and the Atmosphere
        • Unit 5b - The hydrosphere and the Biosphere
      • Unit 6: Our changing home >
        • Unit 6a: Internal Geodynamics
        • Unit 6b: External Geodynamics
    • Laboratory & Tasks
  • MYP Year 8
    • Yr8 Syllabus & Assessment
    • Contents >
      • Units 1, 2 and 3 - Measuring Matters >
        • Unit 1 Physical quantities and Scientific Activity >
          • Converting Units
        • Unit 2 Matter and its Properties
        • Unit 3 Pure Substances and Mixtures >
          • Concentration and units (g/L, % mass)
      • Units 4 and 5 - Chemical Cooking >
        • Models of the Atom
        • Electronic structure of matter.
        • Periodic table (distribution of elements).
        • Chemical formulation
        • Molecular mass
        • Moles
        • Types of reactions
        • Lavoisier's law: Balancing of equations
        • Reaction rates: Factors that affect the speed of a reaction
      • Units 6, 7 and 8 - Move It! >
        • Unit 6 - Motion (URM)
        • Unit 6 - Motion (UARM)
        • Unit 7 - Forces and Mass
        • Unit 8 - Energy and Transformations
    • Laboratory & Tasks >
      • How to write a lab report
  • MYP Year 9
    • Yr9 Syllabus & Assessment
    • Contents >
      • Unit 1 - General organization of the human body, health and illness >
        • Human cells: levels of organisation
        • Health and types of diseases
        • Preventing diseases
        • The Immune System
        • Transplants
        • Addictive substances and associated substances
        • Complete Unit 1
      • Unit 2 - Nutrition >
        • Nutrition and nutrients
        • The Mediterranean diet
        • The anatomy and physiology of the digestive system
        • The anatomy and physiology of the circulatory system >
          • Revision quizzes
        • The anatomy and physiology of the respiratory system
        • The anatomy and physiology of the excretory system
        • Nutrition Documentaries
      • Unit 3 - Interaction and Coordination >
        • The function and anatomy of the nervous system
        • The endocrine system
      • Unit 4 - The reproductive system >
        • Anatomy and physiology of the human reproductive system.
        • Gametogenesis
        • Menstrual cycle
        • Fertilization
        • Infertility, contraception and STDs
      • Unit 5 - Genetics >
        • DNA and genetic modification
        • Cells and Inheritance
        • MORE ON MITOSIS VS MEIOSIS
        • Mendelian genetics
      • Unit 6 - Evolution >
        • Evolutionary theories
        • Evolution Simulators
      • EXTRA Unit 7 - Ecology and the environment >
        • Ecology
    • Laboratory & Tasks
  • MYP Year 10
    • Yr10 Syllabus
    • Contents >
      • Unit 0 - Formulation
      • Unit 1 - Scientific Activity
      • Unit 2 - Kinetic theory
      • The Atmosphere
      • Unit 3 - Mixtures and pures substances: Colligative properties
      • Unit 4 - The structure of matter
      • Unit 5 - Stoichiometry
      • Unit 6 - Redox Reactions
      • Unit 7 - Movement
      • Unit 8 - Forces
      • Unit 9 - Electricity
      • Unit 10 - Energy
    • Revision
    • Assessments and Lab Sessionss >
      • Assessments >
        • Criterion D - Water crisis
      • Session 1 - Paper balls
      • Sessions 2 - Properties of substances
      • Session 3 - Preparing a Schlenk tube
      • Session 4 - Gas constant
      • Session 5 - Colligative properties
      • Session 6 - Job´s method
      • Session 7 - Redox titration
      • Session 8 - UARM
      • Session 9 - Hooke´s Law
    • PISA questions
  • DP Biology SL
    • Contents >
      • Topic 1: Cell biology >
        • 1.1 Introduction to cells
        • 1.2 Ultrastructure of cells
        • 1.3 Membrane structure
        • 1.4 Membrane transport
        • 1.5 The origin of cells
        • 1.6 Cell division
      • Topic 2: Molecular biology >
        • 2.1 Molecules to metabolism
        • 2.2 Water
        • 2.3 Carbohydrates and lipids
        • 2.4 Proteins
        • 2.5 Enzymes
        • 2.6 Structure of DNA and RNA
        • 2.7 DNA replication, transcription and translation
        • 2.8 Cell respiration
        • 2.9 Photosynthesis
      • Topic 3: Genetics >
        • 3.1 Genes
        • 3.2 Chromosomes
        • 3.3 Meiosis
        • 3.4 Inheritance
        • 3.5 Genetic modification and biotechnology
      • Topic 4: Ecology >
        • 4.1 Species, communities and ecosystems
        • 4.2 Energy flow
        • 4.3 Carbon cycling
        • 4.4 Climate change
      • C: Ecology and conservation >
        • C.1 Species and communities
        • C.2 Communities and ecosystems
        • C.3 Impacts of humans on ecosystems
        • C.4 Conservation of biodiversity
      • Topic 5: Evolution and biodiversity >
        • 5.1 Evidence for evolution
        • 5.2 Natural selection
        • 5.3 Classification of biodiversity
        • 5.4 Cladistics
      • Topic 6: Human physiology >
        • 6.1 Digestion and absorption
        • 6.2 The blood system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Neurons and synapses
        • 6.6 Hormones, homeostasis and reproduction
    • Labs >
      • Statistical analysis
    • Previous to 2015 >
      • Topic 1: Statistical analysis
      • Topic 2: Cells >
        • 2.1 Cell theory
        • 2.2 Prokaryotic cells
        • 2.3 Eukaryotic cells
        • 2.4 Membranes
        • 2.5 Cell division
      • Option F: Microbes and biotechnology >
        • F1 Diversity of microbes
        • F2 Microbes and the environment
        • F3 Microbes and biotechnology
        • F4 Microbes and food production
      • Topic 5: Ecology and evolution >
        • 5.1 Communities and ecosystems
        • 5.2 The greenhouse effect
        • 5.3 Populations
        • 5.4 Evolution
        • 5.5 Classification
      • Option D: Evolution >
        • D1 Origin of life on Earth
        • D2 Species and speciation
        • D3 Human evolution
      • Topic 3: The chemistry of life >
        • 3.1 Chemical elements and water
        • 3.2 Carbohydrates, lipids and proteins
        • 3.3 DNA structure
        • 3.4 DNA replication
        • 3.5 Transcription and translation
        • 3.6 Enzymes
        • 3.7 Cell respiration
        • 3.8 Photosynthesis
        • TO DELETE
      • Topic 4: Genetics >
        • 4.1 Chromosomes, genes, alleles and mutations
        • 4.2 Meiosis
        • 4.3 Theoretical genetics
        • 4.4 Genetic engineering and biotechnology
      • Topic 6: Human health and physiology >
        • 6.1 Digestion
        • 6.2 The transport system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Nerves, hormones and homeostasis
        • 6.6 Reproduction
    • Tasks >
      • Databases
    • Documents
    • DP Biology Resources
    • Interesting links
  • Biología 12º
    • Bloque 1. Bioquímica
    • Bloque 2. Biología celular
    • Bloque 3. Genética y evolución
    • Bloque 4. Microbiología y biotecnología
    • Bloque 5. Inmunología
  • IB Biología NS
  • IB Chemistry HL
    • Contents >
      • Year 1 >
        • Topic 0 - Formulation
        • Topic 1 - Stoichiometric relationships
        • Topic 2 and 12 - Atomic structure
        • Topic 3 and 13 - Periodicity
        • Topic 4 and 14 - Chemical structure and bonding
        • Topic 5 and 15 - Energetics
        • Topic 10 and 20 - Organic chemistry
      • Year 2 >
        • Topic 6 and 16 - Chemical kinetics
        • Topic 7 and 17 - Equilibrium
        • Topic 8 and 18 - Acids and bases
        • Topic 9 and 19 - Redox processes
        • Topic 11 and 21 - Measurement and data processing
        • Option D - Medicinal chemistry
    • Lab work >
      • SFP Campus lab reports
      • Internal assessment structure
      • Internal Assessment examples
    • Nature of science
    • General revision
    • Selectividad
    • General information
    • Extended Essay
  • Other resources for students
    • Science Fair
    • Science essays >
      • How to Reference
    • Chemical formulation
    • Laboratory >
      • How to write a lab report
      • Microscopy
      • Excel for graphs and calculations >
        • Calculate the mean and SD
        • Drawing graphs
        • Add error bars to excel graphs
      • Lab videos!
    • Further Reading >
      • Women In Science
      • Infographics
    • Proyecto integrado
San Francisco de Paula, Science Department.

UNIT 3  - PURE SUBSTANCES AND MIXTURES

Key concept - Systems - What systems can we use to observe and quanitfy what we see in our everyday life, and how can we communicate this information. 

Related concepts - Form - How can we use scientific models to explain and predict these changes? 

Global concept - Scientific and Technical Innovation - Matter is fundamental to our industrial and technological development, we need to understand its properties to utilise it to our best advantage. 

Key Words:

  • solution
  • solute
  • solvent
  • mixture
  • homogenous
  • heterogenous
  • pure
  • sustance
  • compound
  • element
  • molecule
  • atom
  • solubility
  • concentration
Task guide
The tasks and questions on the Weebly will be coloured to represent the different style of questions that you will find in your exams. The task should be completed in your "Natural Sciences" GoogleDrive document.

Green -   Stating scientific knowledge
Orange - Applying scientific knowledge and understanding
Red -     Analysing and evaluating information

There will also be "extension" tasks for students who finish tasks quickly! Also look out for links to interactive resources and videos.

Pure substances and mixtures

Picture
  (ms deller science, 2017)
​

         How are pure substances and mixtures different?
Mixtures can be homogenous - this means that they are the same all the way through . For example, blood, air.

Or they can be heterogenous - this means they are not the same all the way through,. You can see differences among its parts - they have 'lumps'. For example pizza.
A pure substance always features the same composition and properties throughout (colour, point of fusion etc) and cannot be dissociated into simpler ones by simple physical methods. Water, iron, common salt, sulfuric acid and oxygen are just a few examples of pure substances.
Pure substances can be simple substances or compounds. Simple substances are made of just one type of atom; A piece of gold is made of only gold atoms. While compounds are made of more than one type of atom joined together; pure water or ammonia for example.
On the other hand, mixtures contain more than one substance and have different composition and properties in different parts of the sample. For example, we know that air is made of Nitrogen - 78%, Oxygen - 20%, Argon, Carbon Dioxide and some other gases. Air is a mixture. of different gases. In a mixture, the substances are just mixed together and not chemically combined.
​
Imagen
(Ducksters.com, 2015)
Task 3a Here is a list of substances.:
Chocolate            Carbon dioxide        Soil               Brass               Orange Juice (with pulp)       Carbon               Coca Cola             Steel               Alcohol                Iron

Hydrochloric Acid               Oxygen                          Orange juice (without pulp)           Pizza                  Magnesium           Glucose                 ​Blood


Copy the table below and put the substances in the correct columns. Add 2 more substances of your own to each column. 
Element
Compound
Homogenous Mixture
Heterogenous Mixture


​A solution is a very special example of a homogenous mixture. 

In a solution we have a solvent and a solute, The solute is the thing to be dissolved and the solvent is the thing it dissolves in.

For example if we have sugar in water - a sucrose solution, the solvent would be the water, the sucrose (sugar) would be the solute.

Solutions can be separated, if we have a solid disolved in liquid, by evaporating the liquid you will be left with the solid.

In this image, you can see how a solution, sea water has been separated, the water has evaporated and the salt has been left behind

Task 3b

  1. identify the solute and solvent in this example.
Imagen
(SeaSalt Superstore, 2015)

Separating other mixtures

All mixtures can be separated using the appropriate separation techniques. The separation technique used will depend on the properties of the components of the mixture.
Two solids of different size could be separated using a sieve. A mixture of two liquids can also be separated by decantation, if the liquids don't mix, such as water and oil. But if the liquids mix, such as water and alcohol, we would need to use a different method known as distillation.
A good example of this is with crude oil, which looks like this: This in particular is fractional distillation.
Imagen
(Jones Oil Blog, 2013)
This thick, black solution is heated then the different components are collected at different temperatures, like this:
Imagen
(Cdatacoinmdv.890m.com, 2015)
You may recall from previous years yet another method, this time to separate a mixture of a solid that does not dissolve in a liquid, such as sand and water. Do you remember the name of that technique? Of course you do! Yes indeed, it is filtration.

Solution Concentration

Going back to our sucrose solution from above, we can say that our solution can be diluted or concentrated depending on the amount of solute (the sugar) and solvent (the water) that make up the solution. However, saying that our solution is diluted or very concentrated does  not tell us much about the actual amounts  of solute and solvent.
The concentration of a solution is the relationship between the amounts of solute and solvent. It is a measure of the quantity of solute in a given quantity of solvent or solution. 
There are several ways to express the concentration of a solution. This year we will study two of those: Concentration by weight or Mass concentration, and Mass percent.

Concentration - calculations grams per litre (g/l)

The easiest way to imagine and quantify a solution is to ask two questions:
  1. How much solute is there?
  2. How much solution do we have?
In order to answer these questions we need to think about how we would measure these two quantities:

 The solute can be liquid or gas, but for our purposes we can imagine it is a solid, so we measure its mass, in grams.

The only solvent that we will use this year to make our solution will be water,, so we measure its volume in litres.

So if we want to know how many grams of solute there are per litre of solution we use the formula:

Picture
Where: Mass is measured in grams, and volume is measured in litres, so concentration is measured in g/L



Example Calculations:

1. Find the concentration in g/L for 20 g of NaCl dissolved in 500 L of solution

        Data                                        Equation/Formula                                                               
   20g NaCl                                    
   500 l solution                           mass concentration = g solute/L solution                  
   mass conc. = ?
     
     Calculations

       mass concentration = 20g/500 L = 0.04 g/L

 2. 
How many grams of bromine are needed to make 250 mL of a 4.5 g/L solution?

      Data                                        Equation/Formula                                                               
   g Br= ?                                   
   250 mL solution                           mass conc. = g solute/L solution                   
  mass conc. = 4.5 g/L                    so; g solute = (mass conc. )(L solution)
                                                         
      Calculations
       
              g = 4.5/0.250 = 1.1 g Br
concentration_worksheet_2.pdf
File Size: 287 kb
File Type: pdf
Download File


Concentration calculations - mass percent

another way to measure the concentration of a solution is the ratio of how much of the mass of the solution is provided by the solute. 

If more of the mass is made up by the solute then its mass percent ratio will be higher.

This is given by the formula
Picture
Because the measurement of the mass is both in grams, they cancel and there are no units for this number, it is just a plain %age ratio.

As the mass of the solution is always the mass of the solute plus the mass of the solvent., we add them together to get the formula.. But don't forget that, as it is very important!
Picture
We use 180 mL of pure water and 20g of alcohol to make a solution. What is the mass percent of alcohol of the solution? 

 Data                                                                                           Equation/Formula                                                               
   180 mL of pure water = 180 g                               
   20 g EtOH                                                                          mass % =( g solute/ g solution) * 100                
   mass %. = ?
     
     Calculations

       mass % = 20/ (180 + 20) * 100 = 20/200 * 100 % = 10.0%

Questions
1. What is the mass percent of NaCl (table salt) in a solution prepared by dissolving 450 grams of NaCl in 2420g of water?
2. What is the mass percent of a potassium iodide (KI) solution if it has 105g of KI(solute) in 400g of solution?
3. How many grams of solute are in 35g of a 12% salt solution?
4. I add 45g of table salt (NaCl) to prepare 120g of a salt solution, what is the mass percent of the solution?
5. If I get 500g of solute (KI) from a 60% solution, how many grams of solution did I have?
6. What is the mass percent concentration of a calcium chloride solution, if 578g of calcium chloride are dissolved in 3200g of water?
7. What is the mass percent concentration of a salt solution if 683 grams of salt are dissolved in water to make 950g of solution?
8. If I have a 37% zinc chloride solution, how many grams of zinc chloride are in 350g of solution?
9. I want to prepare a 70% NaCl solution. How many grams of salt do I need if I want 80g of solution?

Solubility 

I am sure you have heard that term before. But what does it mean? 
Let's go back once again to our sucrose solution. If we keep on adding sugar to our mixture, eventually the sugar will no longer dissolve in the water, but instead it will settle at the bottom of the glass. At this point we have saturated our solution
So, at that particular temperature no more sugar can be dissolved in that amount of water. The solution has reached its maximum capacity of solubility.
So we can define solubility as the maximum amount of solute that will dissolve in a solvent at a given temperature..

REFERENCES

Cdatacoinmdv.890m.com,. (2015). Result Of Factory Apprentice54 Batch | Cracked Data Coin Money. Retrieved 6 July 2015, from http://cdatacoinmdv.890m.com/result/result-of-factory-apprentice54-batch.html

Ducksters.com,. (2015). Chemistry for Kids: Chemical Mixtures. Retrieved 6 July 2015, from http://www.ducksters.com/science/chemistry/chemical_mixtures.php

Jones Oil Blog,. (2013). The Black Gold Rush: Where’s All the Oil? - Jones Oil Blog. Retrieved 6 July 2015, from http://www.jonesoil.ie/blog/the-black-gold-rush-wheres-all-the-oil/

SeaSalt Superstore, L. (2015). Salt History. Seasaltsuperstore.com. Retrieved 6 July 2015, from http://www.seasaltsuperstore.com/salt-history.aspx
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