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Many chemical reactions occur around the home.

– Describe one chemical reaction that occurs in a home and the

products of the reaction.

A chemical reaction that occurs around the home is the burning of charcoal for barbecues. When

charcoal burns, it reacts with oxygen to form ash, carbon dioxide, and heat.

The cooking of food is another example.

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Copper sulfate, when dissolved in water, has a blue color. When steel wool is mixed

with a copper sulfate solution, the steel wool disappears, a brownish solid forms,

and the color of the solution changes from blue to green.

– Explain how three changes that occur in this experiment suggest a new

substance may have been formed.

The disappearance of the steel wool suggests that a new substance is forming. As steel does not dissolve in water, it is likely that it was part of the reaction that formed a new substance. Another new substance, the brown solid, was

observed forming. Because it is different in color from the other substances, it is also

probably a new substance. The color change of the solution from blue to green implies that

a chemical change has taken place.

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List the four signs of a chemical reaction

1. Formation of a gas

2. Formation of a precipitate (solid in a liquid)

3. Color change

4. Energy change

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Describe the difference between ionic and covalent

bonding.

Ionic bonding is the gaining or losing of electrons in atoms to make happy atoms.

Covalent bonding is the sharing of electrons between atoms to make happy atoms.

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What happens to atoms during a chemical

reaction?

Chemical reactions occur when different atoms and molecules combine together and spit

apart.

Atoms are re-arranged in the way they are connected (or bonded); they are not created or

destroyed.

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Explain the difference between chemical and

physical changes.

PHYSICAL REACTION – is a change that affects the size, shape or color of a substance but does not affect its composition – no new substance is formed

Examples might by melting, boiling, cutting, etc.

CHEMICAL REACTION – is a change caused by the rearrangement of the atoms of one or more substances, resulting in the formation of new substances, having entirely different properties.

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State the Law of Conservation of Mass

Matter cannot be created or destroyed in an ordinary chemical reaction.

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Describe endothermic and exothermic

Endothermic – absorbing energy

Exothermic – releasing energy

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A student wrote the following equation:

4Al + 3O2 2Al2O3

– Write a sentence to describe what occurs in this reaction.

In this reaction, aluminum reacts with oxygen to form Al2O3.

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Students carry out a chemical reaction by mixing two solutions in a glass beaker. A temperature

probe in the beaker records changes in temperature that occur after mixing. Within

seconds after mixing, the temperature rises from 25 °C to 40 °C. Then the temperature returns to 25

°C over a period of several minutes.

–Based on this data, what should be concluded about the type of chemical reaction that has

occurred?

The best conclusion is that an exothermic reaction has occurred. The students

observe the temperature rising by 15 °C soon after they mix the chemicals. This shows that the reaction has given off

energy as heat. Although there is cooling afterward, that is normal. Any hot object

cools as it gives off heat.

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Betsy mixes and stirs two chemical solids together. While stirring she

notices that the beaker is getting hot. What is happening to the beaker?

The reaction of the two chemicals is releasing heat – an EXOTHERMIC

reaction