1. Unit 5 Review

2. How many atoms are in 5.2 mol CO2?

3. Find the MW of MgSO4•7H2O. =Mg + S + 4O + 7(H2O)
= (16.00) + 7( )
= g/mol

4. How many grams are in 7.20 moles of dinitrogen trioxide?

5. The density of an unknown gas is 2. 054 g/L at STP
The density of an unknown gas is g/L at STP. (a) What is the molar mass?

6. How many atoms are in 22.0 g of water?

7. Determine the percent composition of C3H8.

8. A 7.0 g sample of calcium nitrate, Ca(NO3) 2•4H2O, is heated to constant mass. How much anhydrous salt remains?

9. Oxalic acid (COOH)2 can be obtained in the laboratory as (COOH)2•2H2O
Oxalic acid (COOH)2 can be obtained in the laboratory as (COOH)2•2H2O. Calculate the percent composition of salt and water.

10. A g sample of Strontium nitrate, Sr(NO3)2nH2O, is heated to a constant mass of g. Calculate the hydration number.

11. The molecular formula for glucose is C6H12O6, its empirical formula is….

12. A compound is analyzed and found to contain 2. 42g aluminum and 2
A compound is analyzed and found to contain 2.42g aluminum and 2.15g oxygen. Calculate its empirical formula.

13. The empirical formula of a compound has a molar mass of 31
The empirical formula of a compound has a molar mass of grams while the molecular formula has a molar mass of grams. What is the multiplying factor? 3

14. How many grams are there in 1.5 x 1025 molecules of CO2?

15. What percentage of water found in Na2S•9H2O?
162.0/240.1*100 = 67.5 %

16. A 3. 0 g sample of Na2CO3•H2O is heated to constant mass
A 3.0 g sample of Na2CO3•H2O is heated to constant mass. How much anhydrous salt remains?
%anhydride = 106.0/124.0*100 = % mass of anhydride = * 3.0 g = 2.6 g

17. A 5. 0g sample of Cu(NO3)2•nH2O is heated, and 3
A 5.0g sample of Cu(NO3)2•nH2O is heated, and 3.9g of the anhydrous salt remains. What is the value of n?
Moles of Cu(NO3)2 = 3.9 g / g/mol = mol
Moles of H2O = 1.1 g / 18.0 g/mol = mol
Convert to lowest whole-number ratio...
Moles of Cu(NO3)2 = mol / mol = 1
Moles of H2O = mol / mol = 2.9 ≈ 3

18. How many ions are in Ca3(PO4)2?5

19. What is the representative particle of NH4Br?
Formula unit

20. How many atoms are in C6H12O6?24

21. Chemical analysis of 2-propanol, also known as isopropanol or rubbing alcohol, indicates that it is 60.0% C, 13.4% H, and 26.6% O. What is its empirical formula?
C3H8O

22. Determine the empirical formula for a compound containing 63.50% Ag, 8.25% N, and 28.25% O.
AgNO3

23. Determine the empirical formula for a compound found to contain 111
Determine the empirical formula for a compound found to contain g of Fe and g of S.
FeS

24. Determine the molecular formula for a compound with a molar mass of 92
Determine the molecular formula for a compound with a molar mass of g/mol that contains g of nitrogen and g of oxygen.
N2O4

25. Determine the molecular formula of a compound having an empirical formula of CH and a molar mass of g/mol.
CH = 13.0 g/mol
actual = 78.1 / 13.0 = 6 →
molecular formula = C6H6