Reactions

Question 1

What happens in an exothermic reaction?

Answer 1

Energy is released into surroundings; the products have less net energy contained than the reactants and feel hot

Question 2

What happens in an endothermic reaction?

Answer 2

Energy is absorbed from surroundings; the products have more net energy contained than the reactants and feel cold

Question 3

What is enthalpy?

Answer 3

The change in heat: product energy - reactant energy

Question 4

What enthalpy do endothermic reactions have?

Answer 4

Positive enthalpy

Question 5

What enthalpy do exothermic reactions have?

Answer 5

Negative enthalpy

Question 6

What type of reaction is photosynthesis?

Answer 6

An endothermic reaction

Question 7

What type of reaction is respiration?

Answer 7

The opposite of photosynthesis, an exothermic reaction

Question 8

General combustion reaction

Answer 8

Complete: C(x)H(y) (O(z)) + O2 —> CO2 + H2O (+ heat)
Incomplete:
C(x)H(y) (O(z)) + O2 —> CO2 + H2O + CO + C (+heat)

Question 9

General combination reaction (metal and nonmetal)

Answer 9

metal + nonmetal —> salt (ionic compound)

Question 10

General combination reaction (metal and oxygen)

Answer 10

metal + O2 —> metal oxide

Question 11

General combination reaction (metal oxide and water)

Answer 11

metal oxide + water —> base

Question 12

General combination reaction (nonmetal and oxygen)

Answer 12

nonmetal + O2 —> nonmetal oxide

Question 13

General combination reaction (nonmetal oxide and water)

Answer 13

nonmetal oxide + water —> acid

Question 14

General decomposition reaction

Answer 14

AB (+ heat) —> A + B

Question 15

General acid-base neutralization

Answer 15

HA + B(OH) —> BA (salt) + water

Question 16

General acid-metal reaction

Answer 16

HA + B —> H2 + BA (salt)

Question 17

General acid-carbonate reaction

Answer 17

HA + B(CO3) —> CO2 + water + BA (salt)

Question 18

Define a chemical reaction

Answer 18

A process in which bonds break and new ones are formed

Question 19

What does a carbonate decompose into?

Answer 19

It will produce CO2, and the remaining O will join the other element

Question 20

What does a metal hydroxide decompose into?

Answer 20

Metal oxide and water

Question 21

Can unstable acids decompose?

Answer 21

Yes, some decompose into nonmetal oxides and water, carbonic acid decomposes at room temperature into CO2 and water

Question 22

What do you call the energy needed to begin a reaction?

Answer 22

Activation energy, the energy difference between the energy of the reactants and the highest point on the arch in a diagram