Balancing Chemical Equations and Mass Calculations

These true/false questions are a quick overview of the topics in this lesson. You are not expected to know this material before hand.

The questions are intended to help you focus on material in the lesson. After you have studied the lesson you should be able to answer these and even more complicated questions.

revised October 12, 2009 all rights reserved Dr. Walt Volland 2005-2009

1. T

The symbols for atoms represent their mass.

2. F

The symbol (s) indicates a soluble material.

3. T

The mass of reactants is more than the mass of products in a chemical equation.

4. F

Subscripts on formulas in chemical equations can be changed to balance the equation.

5. T

The coefficient "1" is generally not written but understood in chemical equations.

6. T

The coefficients in chemical equations are generally written as whole numbers.

7. T

The molar mass of an element equals the atomic weight expressed in grams.

8. F

The molecular mass for H2 is more than the molecular mass for CH4.

9. T

A mole of hydrogen contains the same number of molecules as a mole of anything else.

10. T

The mole is a unit devised to count particles by measuring mass.

11. F

The molar mass to the nearest whole number for hydrogen, H2, is 1. grams.

12. T

The mass of a mole of sodium is more than the molar mass of lithium, Li.

13. F

The equation is balanced CHCH + H2 ---> CH3CH3

14. T

The law of conservation of mass says the total mass of matter in the universe is constant.

15. F

There are 8 "S" atoms in a formula unit of alum, KAl(SO4)2• 12 H2O

16. T

The oxidation number for pure elements is zero.

17. F

If you dried 100 g of alum the weight would stay constant.

18. T

There are 24 "H" atoms in a formula unit of alum, KAl(SO4)2• 12 H2O

19. F

Hydrogen, H2, is a product in the equation CHCH + H2 ---> CH3CH3

20. F

The mole ratio of hydrogen to acetylene is 1 to 1 in the equation CHCH +2 H2 ---> CH3CH3

21. T

The oxidation number for fluorine in compounds is always "-1".

22. T

Oxidation is the loss of electrons.

23. F

Reduction is the loss of electrons.

24. T

This is a neutralization reaction HCl + NaOH ---> NaCl + H2O

25. T

Reactions where a solid is formed that "drops out" of solution are precipitation reactions.


Dr. Walt Volland all rights reserved 2002-2009, revised March 2, 2009