1. What is the % composition of carbon in benzene (C6H6)?
2 slide

2. Total mass of carbon/Total mass of compound
92%

3. How many grams of hydrogen are present in a 10
How many grams of hydrogen are present in a 10.0 g sample of benzene (C6H6)?
2 slides

4. 1) 8% Hydrogen 2) 0.08 x 10.0 g =
0.800 g

5. What is the empirical formula for a compound that is 44% C, 26% N, & 30% O?
3 slides

6. 1) Assume 100. 0 g, so % is changed to grams
1) Assume g, so % is changed to grams. 2) Convert each to moles by dividing by molar mass. 3) Divide each mole quantity by smallest mole quantity. (Rounding may occur.)
C2NO

7. A compound has the empirical formula CH2O and molar mass of 120. 0 g
A compound has the empirical formula CH2O and molar mass of g. What is its molecular formula?
3 slides

8. 1) Mass of CH2O = 30 g/mol 2) 120/30 = 4 3) 4(CH2O) =

9. What is the molarity of a solution that contains 104.4 g KCl in 250 mL?
3 slides

10. 1) Convert mass to moles 104. 4 g KCl x (1 mol/74. 4 g) = 1
1) Convert mass to moles g KCl x (1 mol/74.4 g) = 1.40 mol KCl 2) Convert mL volume to L 250 mL x (1 L/1000 mL) = 0.25 L 3) Divide moles/volume =
5.67 M

11. What mass of KCl is dissolved in 500.0 mL to produce 2.50 M solution?
3 slides

12. 1) Convert mL volume to L ( L) 2) Solve for moles L x (2.50 mol/L) = 1.25 mol 3) Convert moles to grams 1.25 mol x (74.4 g/mol) =
93 g

13. How many moles of CO2 are in 22.0 g?
2 slides

14. 22.0 g x (1 mol/44.0 g) =
0.500 mol

15. How many moles of O2 are in 5.6 L?
2 slides

16. 5.6 L x (1 mol/22.4 L) =
0.25 mol

17. What is the volume occupied by 56.0 g of N2 ?
3 slides

18. 56.0 g x (1 mol/28.0 g) x (22.4 L/mol) =
44.8 L

19. What is the density of O2 ?
2 slides

20. 32.0 g/ 22.4 L =
1.43 g/L

21. What is the molar mass of a gas that has a density of 2.25 g/L?
2 slides

22. (22.4 L/1 mol) x (2.25 g/L) =
50.4 g/mol

23. Use the following reaction: 4NH3 + 3O2  2N2 + 6H2O
How many moles of oxygen, with excess ammonia, can produce 4 moles of nitrogen?
2 slides

24. 4 mol N2 x (3 mol O2 /2 mol N2) =
6 mol O2

25. Use the following reaction: 4NH3 + 3O2  2N2 + 6H2O
How many grams of ammonia are needed to produce 14.0 g of N2?
3 slides

26. 14.0 g N2 x (1 mol N2/28 g) x (4 mol NH3 /2 mol N2 ) x (17 g/1 mol) =

27. Use the following reaction: 4NH3 + 3O2  2N2 + 6H2O
How many grams of water are produced from 44.8 L of O2?
4 slides

28. 44.8 L x (1 mol O2 /22.4 L) x (6 mol H2O/3 mol O2) x (18 g H2 O/1 mol) =

29. Use the following reaction: 4NH3 + 3O2  2N2 + 6H2O
If there are 5.00 moles of ammonia and 5.00 moles of oxygen, how many moles of nitrogen are produced?
4 slides

30. 1) 5. 00 moles of each reactant is what you have 2) 5
1) 5.00 moles of each reactant is what you have 2) 5.00 mol NH3 x (3 mol O2 /4 mol NH3 ) = 3.75 mol O2 is what I need 3) O2 : have (5.00 mol) > need (3.75 mol), so NH3 is limiting reactant 4) mol NH3 x (2 mol N2 / 4 mol NH3 ) =
2.50 mol N2

31. Use the following reaction: 4NH3 + 3O2  2N2 + 6H2O
If excess oxygen reacts with 3.00 mol NH3 , what is the theoretical yield of H2O?
3 slides

32. 3.00 mol NH3 x (6 mol H2O/4 mol NH3) x (18 g/mol) =

33. If 70.0 g of water is produced, what is the percent yield?
2 slides

34. 1) 70.0 g = actual yield 2) 81.0 g = theoretical yield 3) [actual/theoretical] x 100 =
86.4 %

35. Use the following reaction: Fe + 2HCl  FeCl2 + H2
If 20 atoms of iron are dropped into a beaker containing hydrochloric acid, how many molecules of hydrogen would be produced?
2 slides

36. 20 Fe atoms x (1 H2 molecule/1 Fe atom) =
20 H2 molecules