Assignment (1)
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If stomach acid has a pH of 1, and a person took a tums tablet which raised the pH to 3, how much was the
increase in pH?
What is acid rain?
How would we make an acidic lake normal again?
1. How many grams of CaCl2 would be required to produce a 3.5 M
(molar) solution with a volume of 2.0L?
2. If you have 10.0 grams of Br2 and dissolve it in 1.00 L of
cyclohexane, what is the molality of the solution? The density of
cyclohexane is 0.779 kg/l at room temperature.
What is the molality of a 0.123 M HCl(aq) solution? The density of the
solution is 1.030 g/mL.
3. What is the molarity of a 3.21 m KOH(aq) solution? (density of
solution = 1.163 g/mL)
4. Determine the mole fraction of each substance in a solution containing
36 gm of water and 46 gm of glycerin, C3H5(OH)3.
5. calculate the molarity and molality of sulfuric acid solution of a
specific gravity 1.198, containing 27% H2SO4by weight.
6. A solution containing 10 gm acetic acid, CH3COOH, in 125 gm water.
What is the concentration of the solution expressed as
 Mole fraction
 Molarity
 Molality
7. A process containing 75 wt% methane and 25wt% ethane flows at
a rate of 1000 kg/min. what is the flow rate of the process in
mole/min?
8.
You are to design a mixer to produce a 60 wt% isopropanol
solution in water. You are provided 10 mole/min of a 90 mole%
isopropanol stream, and have access to any desired quantity of a 10
mole% isopropanol stream. What is the maximum amount of the
final product stream you can produce? Give your answer in both
mass and mole flow rates. (isopropanol is C3H8O)
Assignment (3)
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Two methanol-water mixtures are contained in separate flasks. The mixture contains 40 wt%
methanol, and the second contains 70 wt% methanol. If 200 g of the first mixture are combined with
150 g of the second, what are the mass and compostion of the product?
One thousand Kilograms per hour of a mixture containing equal parts by mass of benzene (C6H6)
and toluene (C7H8) are distilled. The flow rate of the overhead product stream is 488 Kg/h, and the
bottom stream contains 7.11 wt % benzene. Draw and label a flowchart for the process. Then
calculate the mass and mole fractions of benzene and the molar flow rates of benzene and toluene
(mole/h) in the overhead product stream.
Strawberries contain 15 % solids and water 85 % by mass. To make strawberry jam, crushed
strawberries and sugar are mixed in a 45: 55 ratio, and the mixture is heated to evaporate water
until the residue contains 1/ 3 water by mass. Draw and label a flowchart of this process, and use it
to calculate how many Kgs of strawberries are needed to make 1 Kg of jam
Sheet on Mass Balance with Chemical Reaction
1. 15.00 g aluminum sulfide and 10.00 g water react until the limiting reagent is used up. Here is the balanced
equation for the reaction:
Al2S3 + 6 H2O -----------> 2Al(OH)3 + 3 H2S
a. Which is the limiting reagent?
b. What is the maximum mass of H2S which can be formed from these reagents?
c. How much excess reagent remains after the reaction is complete?
2. A 50.6 g sample of Mg(OH)2 is reacted with 45.0 g of HCl according to the reaction:
Mg(OH)2 + 2 HCl --> MgCl2 + 2 H2O
What is the theoretical yield of MgCl2?
3. Methane (CH4) burns in air (reacts with O2) to form carbon dioxide (CO2) and water vapor (H2O). If 20 g of CH4 was
mixed with 30 g of O2 in a closed container and ignited:
a. What would be the limiting reagent?
b. How much excess reagent would be left over?
c. How much CO2 would be made?
d. How much H2O would be made?
4. For the reaction: K + O2 K2O
a. Is 0.65 moles of O2 enough to react with 0.56 moles of K?
b. Is 0.65 g of O2 enough to react with 0.56 g of K?
c. How many grams of K2O will be produced from 0.5 g of K and 0.1g of O2?
5. For the reaction: Na2O + H2O NaOH
a. What weight of NaOH could be made from 12.4 g of Na2O and 42.1 g of H2O?
b. What would be the limiting reagent if 100 g each of Na2O and H2O were allowed to react?
6. For the reaction: C + H2 CH4
a. How many moles of CH4 can be made from 7.0 moles of H2 and 5.0 moles of C
b. What weight of CH4 will be made when 10.0 g of H2 reacts with 5.0 g of C?
7. You are given the following reaction:
2 H2(g) + O2(g) --> 2 H2O(l)
a. The stoichiometric ratio of moles H2 to moles O2
b. The actual moles H2 to moles O2 when 1.50 mol H2 is mixed with 1.00 mol O2
c. The limiting reactant (H2 or O2) for the mixture in (b)
d. The theoretical yield, in moles, of H2O for the mixture in (b)
8. Zinc and sulphur react to form zinc sulphide according to the equation
Zn + S ---------> ZnS
If 25.0 g of zinc and 30.0 g of sulphur are mixed,
a. Which chemical is the limiting reactant?
b. How many grams of ZnS will be formed?
c. How many grams of the excess reactant will remain after the reaction is over?
9. Sodium hypochlorite is formed according to the reaction:
2NaOH + Cl2 -------► NaOCl + NaCl + H2O
In a continuous reactor by bubbling Cl2 through a concentrated 40 % mass (NaOH) solution. Suppose the solution of
NaOH in H2O is fed at 1000 Kg/hr and the Cl2 gas at 10 Kgmol/hr.
a. Determine which is the limiting reactant?
b. Calculate the outlet composition of the reactor assuming 60% conversion of the limiting reactant?
10. Sodium hypochlorite is formed according to the reaction:
2NaOH + Cl2 -------► NaOCl + NaCl + H2O
In a continuous reactor by bubbling Cl2 through a concentrated 40 % mass (NaOH) solution. Suppose the solution of
NaOH in H2O is fed at 1000 Kg/hr and the Cl2 gas at 10 Kgmol/hr.
a. Determine which is the limiting reactant?
b. Calculate the outlet composition of the reactor assuming 60% conversion of the limiting reactant?