Chemistry A Study Of Matter Review Sheet Unit 12 Answers - Fill ... - Free Printable

Let’s go step by step through each question on the worksheet. I’ll make sure each answer is clear, simple, and correct — just like you’d want for homework help.

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Question 1:

> The basic premise of the collision theory is that particles must first _______________ if a reaction is to occur. Additionally, they must _________________________. To be effective, the particles must _______________ with the _______________, and the proper amount of _______________.

✔ Step-by-step reasoning:

Collision theory says reactions happen when particles bump into each other — but not just any bump! They need:

- To collide (that’s the first blank).
- To collide with enough energy (called activation energy) — so second blank: “have sufficient energy” or similar.
- Also, they must hit in the right way — called proper orientation.
- So third blank: “collide”, fourth: “correct orientation”, fifth: “energy”.

But let’s match standard textbook phrasing:

Standard version:
> Particles must first collide if a reaction is to occur. Additionally, they must have enough energy. To be effective, the particles must collide with the correct orientation, and the proper amount of energy.

Wait — that repeats “collide”. Let me check better wording.

Actually, common fill-in-the-blank version is:

> The basic premise of the collision theory is that particles must first collide if a reaction is to occur. Additionally, they must have sufficient kinetic energy. To be effective, the particles must strike with the proper orientation, and the proper amount of activation energy.

Yes — that’s more precise.

So final answers for Q1:

- collide
- have sufficient energy (or kinetic energy)
- strike (or collide)
- proper orientation
- activation energy

We’ll use the most commonly accepted terms in high school chem.

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Question 2:

> _______________ is the study of reaction rates which is the rate at which the _______________ disappear and the products _______________.

✔ Step-by-step:

This is defining chemical kinetics.

Chemical kinetics = study of how fast reactions happen.

It measures how fast reactants are used up → disappear
and how fast products form → appear

So:

First blank: Chemical kinetics
Second blank: reactants
Third blank: appear

Simple and direct.

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Question 3:

> There are five factors affecting the reaction rate:
a. _______________
b. _______________ of the _______________
c. _______________
d. _______________
e. _______________

✔ Step-by-step:

Five main factors that affect how fast a reaction goes:

1. Nature of the reactants – some substances react faster than others (like sodium vs iron with water)
2. Concentration (for solutions) or pressure (for gases) – more particles = more collisions
3. Temperature – hotter = faster movement = more energetic collisions
4. Surface area – especially for solids; powdered reacts faster than lump
5. Catalysts – speed up reaction without being used up

Now, looking at the blanks:

a. Probably “Nature of reactants”
b. “Concentration” of the “reactants” (or pressure for gases, but concentration is general)
c. Temperature
d. Surface area
e. Catalysts

Sometimes order varies, but this is standard.

Note: Sometimes “physical state” is grouped under nature of reactants, and surface area is separate.

Also, sometimes “presence of catalyst” is listed last.

We’ll go with:

a. Nature of the reactants
b. Concentration of the reactants
c. Temperature
d. Surface area
e. Presence of a catalyst

Perfect.

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Question 4: Use the collision theory to explain:

a. A mixture of hydrogen gas and chlorine gas reacts faster when the volume they occupy is decreased.

✔ Reasoning:

Decreasing volume → increases pressure → increases concentration of gas molecules → more particles per unit space → more frequent collisions → faster reaction.

Collision theory: More collisions = higher chance of effective collisions → faster rate.

So explanation: When volume decreases, gas particles are closer together. This means they collide more often. More collisions mean more chances for successful reactions → reaction speeds up.

b. Iron filings react faster than iron wire.

✔ Reasoning:

Iron filings have much larger surface area than a solid wire. More surface exposed → more places where reactant particles can hit and react → more collisions per second → faster reaction.

Collision theory: Reaction happens at the surface. More surface area = more collision sites → faster rate.

c. An increase in temperature increases the reaction rate.

✔ Reasoning:

Higher temperature → particles move faster → more kinetic energy → two effects:

1. More frequent collisions (because moving faster)
2. More importantly: more particles have enough energy to overcome activation energy barrier → more *effective* collisions

So even if collision frequency only increases a little, the big jump is in the number of particles with enough energy to react.

Thus, reaction rate increases sharply with temperature.

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Question 5:

> Why do you think that industrial chemists are concerned with reaction rates?

✔ Reasoning:

In industry, time = money. If a reaction takes too long, it costs more to run factories, uses more energy, delays production.

They want reactions to go fast enough to be profitable, but also safely and efficiently.

Also, controlling reaction rates helps control product quality, avoid side reactions, save resources.

Examples: Making ammonia (Haber process), sulfuric acid, plastics — all need optimized rates.

So short answer: Because faster reactions mean more product in less time → lower cost → higher profit. Also, safety and efficiency matter.

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Now, compiling all answers neatly.

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Final Answer:

1.
collide
have sufficient energy
strike
proper orientation
activation energy

*(Note: Some textbooks say “collide” again for third blank — both acceptable. We used “strike” to avoid repetition.)*

2.
Chemical kinetics
reactants
appear

3.
a. Nature of the reactants
b. Concentration of the reactants
c. Temperature
d. Surface area
e. Presence of a catalyst

4.
a. Decreasing volume increases concentration of gas particles, leading to more frequent collisions and thus a faster reaction rate.
b. Iron filings have greater surface area than iron wire, allowing more contact points for collisions, increasing the reaction rate.
c. Higher temperature gives particles more kinetic energy, so more collisions occur and more particles have enough energy to react (exceed activation energy), increasing the rate.

5.
Industrial chemists care about reaction rates because faster reactions produce more product in less time, reducing costs and increasing profits. Controlling rates also improves safety, efficiency, and product quality in large-scale manufacturing.