Lessons 13, 15, 18 Test

Question 1

Which of the following substances are soluble in water (Lesson 12)?

Answer 1

Sugar, Sodium Chloride, Kool Aid power

Question 2

What is solubility and what is it affected by?

Answer 2

Solubility: The amount of solute that will dissolve in a solvent at a certain temperature and pressure.
Affected by: temperature and pressure

Question 3

How does changing the amount of solvent affect the amount of solute that will dissolve?

Answer 3

Because if you add more solvent, more solute will dissolve, but if you add less solvent, then less solute will dissolve.

Question 4

How do you determine the solubility of a substance in the lab?

Answer 4

1. Measure water and pour into test tube carefully.
2. Take the mass of the container of solute and record.
3. Add one scoop of solute into the test tube and shake.
4. Repeat step 3 until no more solute can dissolve in the solvent.
5. Subtract the mass of the original container with the mass you have now.
6. That is your answer.

Question 5

What is the difference between a homogenous mixture and a heterogenous mixture?

Answer 5

Homogenous: well mixed
Ex. Kool Aid, sodas
Heterogenous: not well mixed
Ex. Trail mix, chicken noodle soup

Question 6

What are the parts of a solution?

Answer 6

Solvent and solute

Question 7

How do you know when a solution has become saturated?

Answer 7

Because there will be solute on the bottom, and even if you try to dissolve it, it won’t dissolve anymore.

Question 8

How do you calculate how much solute will dissolve in a certain amount of solvent?

Answer 8

Ex) 7.6g/10mL = 3.8g/5mL

Question 9

How can knowing the solubility of a substance help identify the substance?

Answer 9

Solubility is a characteristic property. (Just like density) that can be used to identify a type of matter. If you had an unknown substance , you could find its solubility and use a solubility chart to match it.

Question 10

When is appropriate to use the filtration technique to separate a mixture?

Answer 10

Heterogenous mixture

Question 11

When should you use the evaporation separation technique?

Answer 11

Homogenous mixture

Question 12

Explain the difference between residue and filtrate.

Answer 12

Residue is the substance left behind in the filter paper after filtration while filtrate is the substance that goes through the filter into the test tube.

Question 13

What is desalination?

Answer 13

Process of removing salt from water.

Question 14

What is a characteristic property?

Answer 14

A physical or chemical property that helps us to identify a substance.

Question 15

What are examples of characteristic property?

Answer 15

Density, freezing, melting, boiling, condensing

Question 16

Describe an alloy? Why are they useful?

Answer 16

Alloy: a mixture of solids (typically metals) that have a combination of properties of the solids.
Ex. Aluminum is light but weak, an aluminum alloy is made that is both light and strong.
Useful: plane

Question 17

Explain what happens to the freezing point of water when salt is added .

Answer 17

Salt lowers the freezing point of ice/ water.

Question 18

Why is salt added to the roads in winter?

Answer 18

So it will melt the roads when it’s icy during winter.

Question 19

Explain what happens to the boiling point of water when salt is added.

Answer 19

When salt is added to boiling water, the water stops boiling and then starts to boil at a higher temperature. So, salt increases the the boiling point of water.