1. Which one is a true statement about exothermic reactions?
a. Energy from an outside source is continuously being added
b. The reaction container always feels cold
c. The reactants have more heat energy than the products
d. More heat is given off than is put into the reaction
2. Which one is a true statement about endothermic reactions?
a. Energy from an outside source is continuously being added
b. The reaction container always feels hot
c. The reactants have less heat energy than the products
d. More heat is given off than is put into the reaction
3. Which of the following chemical formulas shows an ionic compound?
a. CO2
b. N2O
c. NaCl
d. C6H12O6
4. Which of the following chemical formulas shows a covalent compound?
a. CO2
b. MgO
c. NaCl
d. HBr
5. How do ionic bonds differ from covalent bonds?
a. Electrons are shared in an ionic bond
b. Electrons are transferred in an ionic bond
c. Protons are shared in an ionic bond
d. Protons are transferred in an ionic bond
6. How do ionic bonds differ from covalent bonds?
a. Electrons are shared in a covalent bond
b. Electrons are transferred in a covalent bond
c. Protons are shared in a covalent bond
d. Protons are transferred in a covalent bond
7. What is true when a reaction has reached equilibrium?
a. The reaction has stopped
b. The reaction is faster in the forward direction
c. The reaction is faster in the reverse direction
d. The reaction rate is equal in both directions
8. What is true when a reaction has reached equilibrium?
a. The concentration of the reactants is changing
b. The concentration of the products is changing
c. The reaction has stopped
d. The concentration of products and reactants is constant
9. If a substance evaporates easily, it is said to be __________.
a. Volatile
b. Condensing
c. Crystallized
d. Changing pigmentation
10. If a substance is changing from a vapor to a liquid, like steam on a mirror, it is said to be __________.
a. Volatile
b. Condensing
c. Crystallized
d. Changing pigmentation
11. Which of these can be classified as a pure substance?
a. Solution
b. Heterogeneous mixture
c. Compound
d. Homogeneous mixture
12. Which of these can be classified as a pure substance?
a. Salt water
b. Salt
c. Pumpkin pie
d. Iced tea
13. The following characteristics describe which of these terms? The substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios.
a. Homogeneous mixtures
b. Heterogeneous mixtures
c. Pure substance
d. Solution
14. The following characteristics describe which of these terms? The substance is mixed uniformly throughout and each part of the substance contains the same ratio of materials with the same properties.
a. Homogeneous mixture
b. Heterogeneous mixture
c. Pure substance
d. Compound
15. Solutions with high pH values have which of these properties?
a. Feels slippery
b. Tastes sour
c. Gives off hydrogen gas when reacted with metal
d. Turns litmus paper red
16. Solutions with low pH values have which of these properties?
a. Feels slippery
b. Tastes sour
c. Have an -OH group
d. Turns litmus paper blue
17. Acids turn litmus paper what color?
a. Red
b. Blue
c. Yellow
d. Pink
18. Bases turn litmus paper what color?
a. Red
b. Blue
c. Yellow
d. Pink
19. Balance the following reaction: CH4 + O2 CO2 + H2O
CH4 + 2 O2 CO2 + 2H2O
20. How do you know if a reaction is endothermic?
An endothermic reaction absorbs energy. It will feel cold because the reaction is absorbing the energy from your skin.
21. How do you know if a reaction is exothermic?
An exothermic reaction releases energy. It will feel hot because the reaction is releasing the energy to your skin.
Answer: 1). D. More heat is given off than is put into the reaction.
"An exothermic reaction is a chemical reaction that releases energy through light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants → products + energy."
