Moles Pre-test.pdf

Name: ______________________ Class: _________________ Date: _________ID: AMoles Pre-TestTrue/FalseIndicate whether the sentence or statement is true or false.____1. The formula of a compound that expresses the smallest whole-number ratio ofthe atoms present is called the empirical formula____2. The empirical formula and the molecular formula for a compound cannot be thesameMultiple ChoiceIdentify the letter of the choice that best completes the statement or answers the question.____3. 1 mole of oxygen atoms representsa. 6.02 x 10^23 atoms d. 1.00 gb. 16 atoms e. None of the abovec. 32.0 g____4. Which represents the greatest number of atoms?a. 50.0 g Zn d. 50.0 g Cub. 50.0 g Al e. all the samec. 50.0 g Fe____5. Which represents the greatest mass?a. 1.0 mol Zn d. 1.0 mol Feb. 1.0 mol Cu e. all the samec. 1.0 mol Al1

Name: ______________________ID: A____ 6. Calculate the molar mass of a sample if a single molecule weighs 5.34 x 10^-23ga. 12.0 g/mol c. 1.13 x 10^46 g/molb. 32.2 g/mol d. 5.34 x 10^-23 g/mol____ 7. Calculate the mass of 20.0 moles of He (in g)a. 5.00 d. 80.1b. 1.20 x 10^25 e. 6.02 x 10^23c. 1.00____8. A 20.0 g sample of Ca contains how many calcium atoms?a. 20.0 atoms d. 40.1 atomsb. 6.02 x 10^23 atoms e. 0.500 atomsc. 3.0 x 10^23 atoms____9. The molar mass of calcium phosphate isa. 175.13 g/mol d. 310.18 g/molb. 324.99 g/mol e. none of the abovec. 135.05 g/mol____10. The molar mass of glucose, C6H12O6 isa. 180 g/molol c. 29 g/moleb. 169 g/mol d. 6.02 x 10^23 g/m2

Name: ______________________ID: A____11. The mass in grams of molecular hydrogen (hydrogen gas) isa. 6 x 10^23 d. 12 gb. 6.0 g e. none of the abovec. 12.0 x 10^23____ 12. How many molecules of O2 are there in 4.0 mol of O2?a. 1.9 x 10^25 d. 2.4 x 10^24b. 128 e. 64c. 6.6 x 10^-24____13. 1 mole of oxygen molecules contains how many moles of oxygen atoms?a. 1.204 x 10^24 d. 6.02 x 10^23b. 3.01 x 10^23 e. 32c. 16____14. Convert 48 g O2 to mole O2a. 0.75 mol d. 3.0 molb. 3 x10^23 mol e. 1.5 molc. 1.5 x 10^-23 mol____15. Consider separate 100g samples of each of the following: NH3, N2O, HCN, N2H4,and HNO3. Which of the samples has the LEAST mass of nitrogen?a. HCN d. NH3b. N2H4 e. N2Oc. HNO33

Name: ______________________ID: A____16. The mass percent of oxygen is in CaO isa. cannot be determined from the d. 25.0%information givenb. 50% e. 72.4%c. 28.5%____17. Vinegar contains carbon, hydrogen, and oxygen with percent masses of 40.01% Cand 6.70% H. If the molar mass of vinegar is about 60 g/mol, what is itsmolecular formula?a. C2H4O2 d. C3H8Ob. CH2O e. C2H20Oc. C3H7O3____18. A compound has a molar mass of 100g/mol and the percent composition (bymass) of 65.4 % C, 5.45% H and 29.09% O. Determine the empirical formula andthe moleculara. CH4O and C3H12O3 d. C3H3O and C6H6O2b. C3HO and C6H2O2 e. CHO and C6H6O6c. CH2O and C4H8O4Numeric Response19. A sample containing 4.90 mol of Ag has a mass of __________g4

Name: ______________________ID: A20. A 18.4 g sample of Au contains how many atoms?21. Calculate the percentage composition (by mass) of all the elements in Cd3(AsO4)22. Determine the percentage composition (by mass) of H2SO423. Determine the percentage composition (by mass) of NH4NO3Short Answer24. Determine the empirical formula of a compound containing 54.2% F and 45.8%S(by mass)5

Name: ______________________ID: A25. A compound contains 12.8 % C, 2.1% H, and 85.1% Br (by mass). Calculate theempirical formula and the molecular formula of the compound given that he molarmass is 237 g/mol.6

ID: AMoles Pre-TestAnswer SectionTRUE/FALSE1. ANS: T2. ANS: FMULTIPLE CHOICE3. ANS: A4. ANS: B5. ANS: A6. ANS: B7. ANS: D8. ANS: C9. ANS: D10. ANS: A11. ANS: D12. ANS: D13. ANS: A14. ANS: E15. ANS: C16. ANS: C17. ANS: A18. ANS: DNUMERIC RESPONSE19. ANS:52920. ANS:5.62 x 10^22 atoms21. ANS:54.8%Cd, 24.4% As, 20.8% O1

ID: A22. ANS:2.06% H; 32.69% S; 65.25% O23. ANS:35.00 % N; 59.96% O; 5.04% HSHORT ANSWER24. ANS:SF225. ANS:Empirical formula = CH2Br;Molecular formula = C2H4Br22