Mole calculations WS #4
Chemistry 11
1. What is the difference between MOLAR MASS and molecular mass?
2. How many molecules are there in one mole of gas at STP?
3. Calculate the molar mass of the following compounds:
a) Calcium Bicarbonate (compound found in hard water)
ans:__________
b) Iron II Sulphate (iron pills )
ans: __________
c) Dinitrogen monoxide ( anesthetic commonly known as "laughing gas")
ans: __________
d) C6H12O6 (sugar)
ans: ___________
4. Solve the following problems:
a) Calculate the number of moles of Helium gas used to inflate a 2.0 L balloon at STP? How
many helium atoms are present in the balloon?
ans: ___________ ans: ___________
b) What is the volume at STP of 20.0 ton of Sulfur Dioxide gas released as a pollutant into the
air by a tar-sands plants in Alberta? ( 1 ton = 1000kg)
ans: ____________
c) A beaker has a mass of 125.0 g. A student then added all the Copper synthesized (to make )
in a chemical reaction into the beaker. The total mass of the beaker when the sample was
added was 135.17 g. Determine the number of moles of Copper produced in the reaction.
ans: ____________
d) A sample containing 0.250 moles of Ammonium Sulphate is required for a reaction. What
is the mass of ammonium Sulphate you need to measure to obtain the required amount of
ammonium sulphate?
ans: _____________
e) What is the mass of 1.20 x 1025 carbon tetrachloride molecules?
ans: _____________
f) To determine the composition of rust, a student collected 31.0 grams of rust. The student
then heated the rust causing the 'release' of oxygen. She then found that her sample contained
21.7 grams of iron. Determine the empirical formula of rust.
ans: _______________
g) A sample of carbon reacts with a 9.2 grams sample of hydrogen to form gaseous compound
that has a mass of 120.0 grams. What is the molecular formula of this hydrocarbon (compound
containing only hydrogen and carbon) which has a molar mass of 26.0 grams?
ans: ________________
5.
How many molecules are there in 5.0 x10 1 g of NOCl(g) at STP?
ans: ________________
6.
What is the volume at STP of 5.74 x 10 21 molecules of SbH3(g)?
ans: ________________
7.
How many atoms of nitrogen are there in 2.08L of ammonia (NH3(g)) at STP?
ans: ________________
5.
a) How many moles of H2SO4 are in 0.50 L of a 1.55M H2SO4 solution?
b) What is the mass of H2SO4 in this solution?
ans: _______________ b)
______________
6. What volume of 0.400M solution of glucose ( C6H12O6 ) is required to obtain 36.0 g of
glucose?
ans: _______________________
7. What is the molarity (concentration) of the resulting solution when 1.47 g of KOH are
dissolved in water and made up to a volume of 500.0 mL?
ans: ________________________
8. Acetylene gas is used for welding. Acetylene contains 30g of carbon for each 2.5 g of
hydrogen. What is the empirical formula for acetylene?
ans: _______________________
9. Describe how you would prepare a 2.50 L of 0.35M solution of sodium sulfate.
ans: ________________________
10. How many moles of Iron (III) chloride could be made with 1.81 x 10 23 atoms of chlorine and
the appropriate number of iron atoms?
ans: _____________________
Evaluation:
Each person submits one evaluation:
Name of the members of the group:
My name:
1) _________________________________
2) _________________________________
3) _________________________________
Evaluation of the group:
* when assessing my group as individuals, I should keep in mind:
- who stayed on task
- who was involved in learning the material
- contributions by each member in helping others understand, asking questions, etc.
- organization of the group and work
* For each person and yourself assess a score from 1 (low) to 5 ( high ) and explain why.
members of my group :
1) ___________________________________ 1
2
3
4
5
why?
2) ___________________________________ 1
2
3
4
5
why?
3) me:________________________________ 1
2
3
4
5
why?
After completing the Review of Chapter 4 and then checking the answers, our group got a score
of ____________________________ out of a maximum of 15. ( one mark each )
After reflecting about the problems, I still have questions regarding the following type of
questions: ( e.g.. finding empirical formula, I always forget to show work, sig fig )
more evaluation:
I would like to work with the same group: circle one
never
sure, why not!
love to!
I thought that the group worked well (not well) together was because:
I would like to work with the following person in the future:
because:
Since the test is on Wednesday, February 15, and I know there won’t be a chance to write it some
other time, these are the steps I need to follow to do really well in the test:
Complete the table:
( be as specific as possible. For example: review empirical formula during break at Fiddler
rehearsal, see teacher during lunch on Tuesday , etc. )
Monday, Feb. 13
Tuesday Feb. 14
During school time
Wednesday Feb. 15
Test time
Class review
Right after classes
After Dinner
Submit this evaluation on Wedneday, Feb. 15, just before the test. No lates!!
Evaluation by the teacher:
Your group worked well together :
1
2
3
4
5
All thequestion in the evaluation form were completed:
1
2
3
4
5
Final mark for the activity:
total mark out of 40: __________
final mark out of 10:
_________