Pure Substances & Purity
What is a pure substance?
A substance made of only one type of particle (elements or compounds).
What is formed when a solute dissolves in a solvent?
A solution.
Does a concentrated solution have more or fewer solute particles than a dilute solution?
More particles.
What happens to the solubility of most solids as water temperature increases
It increases / more solid dissolves
What is the variable that you measure in an investigation?
Dependent variable.
Give one example of a pure substance.
Distilled water (or gold/diamond)
What word describes a solid that can dissolve in a liquid?
Soluble
Calculate the concentration in g/100 cm³ if 6.0 g of sugar is in 20 cm³ of water
30 g/100 cm³
In an experiment measuring how salt dissolves at different water temperatures, what is the independent variable
Temperature of water
What are the variables that you keep the same in an experiment?
Control variables.
What is a mixture?
Two or more substances mixed together that are not chemically bonded.
What word describes a solid that cannot dissolve in a liquid?
Insoluble
Calculate the concentration in g/100 cm³ if 0.5 g of sugar is in 10 cm³ of wate
5 g/100 cm³.
What term describes a solid that dissolves in a solvent?
soluble
What is the variable that you change in an investigation?
Independent variable.
A solid has a total mass of 12.0 g and contains 10.8 g of pure sugar. What is the percentage purity?
90%
What do we call a solution where no more solute can dissolve at a given temperature?
A saturated solution
Solution A has 5 g/100 cm³ and Solution B has 4 g/100 cm³. Which has fewer sugar particles?
Solution B.
What is a solid that does not dissolve in a solvent called?
Insoluble.
What happens if you keep adding a soluble solid to a beaker of water?
It reaches a point where no more solid will dissolve.
A gold alloy has a mass of 200 g and contains 86.5 g of pure gold. What is the percentage of gold?
43.25%
Blue food dye dissolves in water. Which is the solute and which is the solvent?
Blue food dye is the solute, and water is the solvent.
: In the analogy of children in a room for concentration, what models a high concentration solution?
Many children in a room
According to the particle theory, how does the number of solute particles differ between a concentrated solution and a dilute solution?
: A concentrated solution has more solute particles dissolved in a given volume of solvent than a dilute solution.
Why do different soluble substances dissolve in different amounts in the same volume of water?
Because different substances have different levels of solubility (such as sodium chloride compared to lead chloride)