26. A chemist is trying to get two substances to react, but he is unsuccessful. He knows that the two substances should react with one another. Which of the following could he do to possibly get the substances to react? (Select all that apply)

Question

a
decrease the concentration of one of the substances
b
crush up one of the substances
c
cool the substances
d
heat the substances
e
increase the concentration of one of the substances

27. Match the following equations to the type of reaction.
Column A
1. Synthesis
2.Single replacement
3. Combustion
4. Double displacement
5. Decomposition

Column B
a. 2 NaCl + Br2 → 2 NaBr2 + Cl2
b. 2 H2O → 2 H2 + O2
c. Na + Cl → NaCl
d. MgBr2 + 2 NaCl → MgCl2 + 2 NaBr
e. C3H8 + 5 O2 → 3 CO2 + 4 H2O

28. An isotope of the element nitrogen has 7 protons and 9 neutrons. What is the name of the isotope?

a
Nitrogen-7
b
Nitrogen-16
c
Nitrogen-9
d
Nitrogen-14

29. Look at the following equation.
________ Fe + ________ Cl2 → ________ FeCl3

In order to follow the law of conservation of mass, this equation must have which set of coefficients, in order from left to right?

Answer 1

Question 26

To possibly get the two substances to react, the chemist could:

b - crush up one of the substances (increasing surface area can increase reaction rates)
d - heat the substances (increasing temperature generally increases reaction rates)
e - increase the concentration of one of the substances (more molecules can increase the likelihood of a reaction)

Question 27

Match the following equations to the type of reaction:

1. Synthesis - c. Na + Cl → NaCl
2. Single replacement - a. 2 NaCl + Br2 → 2 NaBr2 + Cl2
3. Combustion - e. C3H8 + 5 O2 → 3 CO2 + 4 H2O
4. Double displacement - d. MgBr2 + 2 NaCl → MgCl2 + 2 NaBr
5. Decomposition - b. 2 H2O → 2 H2 + O2

Question 28

An isotope of the element nitrogen has 7 protons and 9 neutrons. The name of the isotope is:

b - Nitrogen-16 (The mass number is the sum of protons and neutrons: 7 protons + 9 neutrons = 16)

Question 29

The balanced equation is:

4 Fe + 3 Cl2 → 4 FeCl3

So the set of coefficients, in order from left to right, is: 4, 3, 4.