Homework Moles, Molarity, and Chemical Equations

[Pages:3]Homework Moles, Molarity, and Chemical Equations

1.) What mass of calcium chloride, CaCl2, is needed to prepare 2.000 L of a 1.73 M solution? (384 g)

2.) A 55.8g sample of SrCl2 is dissolved in 112.5 mL of solution. Calculate the molarity of this solution. (3.13 M)

3.) What mass of solute is contained in 256 mL of a 0.889 M ammonium chloride solution? (12.2 g)

4.) How many moles of insulin are needed to make up 45 mL of 0.0060 M insulin solution? (0.00027 mol)

5.) How many grams of NaCl are contained in 350. mL of a 0.198 M solution of sodium chloride? (4.05 g)

6.) What volume of 18 M sulfuric acid must be used to prepare 2.00 L of 0.200 M H2SO4? (22 mL)

7.) 1.00 mL of a 3.80 x 10?4 M solution of oleic acid is diluted with 9.00 mL of petroleum ether, forming solution A. Then 2.00 mL of solution A is diluted with 8.00 mL of petroleum ether, forming solution B. What is the concentration of oleic acid in solution B? (7.60 x 10?6 M)

8.) A 70.28g sample of Ba(OH)2 is dissolved in enough water to make 2.300 liters of solution. How many mL of this solution must be diluted with water in order to make 1.000 L of 0.100 M Ba(OH)2? (561 mL)

9.) A 230.0mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.14 M. What volume of solvent has evaporated from the 0.275 M solution? (174.5 mL)

10.) 1.00 mL of a 3.60 x 10?4 M solution of oleic acid is diluted with 9.00 mL of petroleum ether, forming solution A. Then 2.00 mL of solution A is diluted with 8.00 mL of petroleum ether, forming solution B. How many grams of oleic acid are in 5.00 mL of solution B? (Molar mass for oleic acid = 282 g/mol) (1.02 x 10?5 g)

11.) A hypothetical element consists of two isotopes of masses 84.95 amu and 86.95 amu with abundances of 37.1% and 62.9%, respectively. What is the average atomic mass of this element? (86.2 amu)

12.) Naturally occurring element X exists in three isotopic forms: X28 (27.977 amu, 92.23% abundance), X29 (28.976 amu, 4.67% abundance), and X30 (29.974 amu, 3.10% abundance). Calculate the average atomic mass of X. (28.09 amu)

13.) The average atomic mass of rhenium is 186.2. Given that 37.1% of natural rhenium is rhenium185, what is the other stable isotope? (187Rh)

14.) Naturally occurring copper exists in two isotopic forms: 63Cu and 65Cu. The average atomic mass of copper is 63.55 amu. What is the approximate natural abundance of 63Cu? (70%)

15.) Naturally occurring element X exists in three isotopic forms: X28 (27.977 amu, 92.23% abundance), X29 (28.976 amu, 4.67% abundance), and X30 (29.974 amu, 3.10% abundance). What is the identity of element X? (Si)

16.) What is the mass of 7 atom(s) of copper in grams? (7.39 x 10?22g)

17.) Iron is biologically important in the transport of oxygen by red blood cells from the lungs to the various organs of the body. In the blood of an adult human, there are approximately 2.62 x 1013 red blood cells with a total of 2.90 g of iron. On the average, how many iron atoms are present in each red blood cell? (molar mass Fe = 55.85 g/mol) (1.19 x 109 atoms)

18.) Roundup, an herbicide manufactured by Monsanto, has the formula C3H8NO5P. How many moles of molecules are there in a 321.0g sample of Roundup? (1.899 moles)

19.) What is the mass of a 9.402mol sample of sodium hydroxide? (376.1 g)

20.) NaHCO3 is the active ingredient in baking soda. How many grams of oxygen atoms are in 0.79 g of NaHCO3? (0.45 g oxygen atoms)

21.) A sample of ammonia has a mass of 28.5 g. How many molecules are in this sample? (1.01 x 1024 molecules)

22.) Phosphorus has the molecular formula P4, and sulfur has the molecular formula S8. How many grams of phosphorus contain the same number of molecules as 2.97 g of sulfur? (1.43 g phosphorous)

23.) A given sample of a xenon fluoride compound contains molecules of a single type XeFn, where n is some whole number. Given that 9.3 x 1020 molecules of XeFn weigh 0.379 g, calculate n. (6)

24.) How many oxygen atoms are there in 8.77 ng of Ca3(PO4)2? (1.36 x 1014 oxygen atoms)

25.) One molecule of a compound weighs 2.33 ? 10?22 g. What is the molar mass of this compound? (140. g/mol)

26.) What is the molar mass of pentanol (C5H11OH)? (88.15 g/mol)

27.) What is the molar mass of Ca3(PO4)2? (310.18 g/mol)

28.) Calculate the molar mass of barium nitrite. (229.35 g/mol)

29.) What is the coefficient for water when the following equation is balanced?(6) As(OH)3(s) + H2SO4(aq) As2(SO4)3(aq) + H2O(l)

30.) What is the coefficient for oxygen when the following equation is balanced?(7) NH3(g) + O2(g) NO2(g) + H2O(g)

31.) Determine the coefficient for O2 when the following equation is balanced in standard form (smallest whole numbers). (19)

C6H14(g) + O2(g) CO2(g) + H2O(g)

32.) What is the sum of the coefficients of the following equation when it is balanced using smallest whole numbers? (9)

NaNH2 + NaNO3 NaN3 +NaOH + NH3

33.) Give (in order) the correct coefficients to balance the following reaction: (1,2,1,6) H2SnCl6 + H2S SnS2 + HCl

34.) When the equation C8H18 + O2 CO2 + H2O is balanced with the smallest set of integers, what is the sum of the coefficients? (61)

35.) The correct coefficients to balance the following reaction are, in order: (3, 5, 3, 5, 5) I2O5 + H2S I2 + SO2 + H2O

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