Matters and Properties of Matters Exam 3 and Problem Solutions

Matters and Properties of Matters Exam 3 and Problem Solutions

1. Which ones of following situations are physical changes?

I. Freezing of water

II. Oxidation of copper

III. Solvation of sugar in water

Solution:

In freezing of water and solvation of sugar, molecular structure of matters stay constant and during these changes no new matters are formed. Thus, they are physical changes. On the contrary, oxidation of copper is chemical change.

2. Which ones of the following graphs are true for pure liquid under constant temperature?

Solution:

Density of liquid is found with formula;

d=m/V

Thus, under constant temperature, when we increase mass of matter, volume of it also increases. In other word, mass and volume are directly proportional to each other. I is true.

Under constant temperature, density of matters do not change. It must stay constant. So, II is false.

Density of matters stay constant under constant temperature, so III is true.

3. There are two closed containers having same liquid. If their vapor pressures are same but vaporization speeds are different, which one of the following factors can explain this situation.

I. Temperature

II. Mass

III. Surface area

Solution:

Temperature affects both vapor pressure and vaporization speed. Increasing in the temperature increases vapor pressure and vaporization speed.

Mass does not affect vapor pressure and vaporization speed.

Surface area affects vaporization speed but it does not affect vapor pressure. Thus, matter having larger surface area has larger vaporization speed.

Only III can explain this difference.

4. Find relation between boiling points of following matters.

Solution:

Boiling point is related to atmospheric pressure. It increases as the atmospheric pressure increase.

Thus, Y has the highest boiling point since it is not pure and atmospheric pressure is high. Then, X and Z are both pure matters but atmospheric pressure of Z is higher than X. So, boiling point of Z is higher than X. Relation becomes;

Y > Z > X

5. Naphthalene is a matter that takes heat and sublimate. Some naphthalene is put into container having constant volume and heated until all of it sublimates. Which ones of the following quantities increase after this process.

I. Density

II. Volume

III. Distances between particles of naphtalene

Solution:

When phase of naphthalene changes from solid to gas, distances between molecules increase and volume of it also increases. Since, mass of naphthalene stays constant, increasing volume decreases density.

II and III increses

6. Write formulas of following compounds.

I. Phosphorus trihydride

II. Barium bromide

III. Disulfur decafloride

IV. Potassium chlorite

Solution:

I. Phosphorus trihydride  : PH₃

II. Barium bromide : BaBr₂

III. Disulfur decafloride : S₂F₁₀

IV. Potassium chlorite: KClO₂