1.
How many grams of Calcium are present in 2.3 moles?
Correct Answer
A. 92.18 g
Explanation
Grams will be a larger number than moles.
So, to calculate moles and MULTIPLY it by molar mass.
(Hint: Think multiplication to get a larger number).
1St: Find the molar mass of Calcium (look on the periodic table): 40.08 g
2nd: Multiply the number of moles by the molar mass: 40.08 x 2.3
2.
How many grams of NaCl is present in 6.3 moles?
Correct Answer
B. 368.17 g
Explanation
Grams will be a larger number than moles.
So, to calculate moles and MULTIPLY it by molar mass.
(Hint: Think multiplication to get a larger number).
1St: Find the molar mass of NaCl: Na 22.99 + 35.45 = 58.44 g
2nd: Multiply the number of moles by the molar mass: 6.3 x 58.44 g/mol = 368.17
3.
How many grams are in 2.3 moles of Na_{2}SO_{4}? (The molar mass of Na_{2}SO_{4} is 142.05g/mol)
Correct Answer
B. 326.72 g
Explanation
Grams will be a larger number than moles.
So, to calculate moles and MULTIPLY it by molar mass.
Multiply the number of moles by the molar mass: 2.3 x 142.05 g/mol = 326.72 g
4.
How many grams of NH_{3} are in 9.2 moles? (The molar mass of NH_{3}= 17.03 g/mol)
Correct Answer
C. 156.68 g
Explanation
Grams will be a larger number than moles.
So, to calculate moles and MULTIPLY it by molar mass.
Multiply the number of moles by the molar mass: 9.2 x 17.03 = 156.68 g
5.
How many grams of LiCl are in 6.7 moles? (The molar mass of LiCl = 42.39 g/mol)
Correct Answer
D. 284.01 g
Explanation
Grams will be a larger number than moles.
So, to calculate moles and MULTIPLY it by molar mass.
Multiply the number of moles by the molar mass: 6.7 x 42.39 g/mol = 284.01 g
6.
How many moles of LiBr are there in 486.30 g of LiBr? (The molar mass of LiBr = 86.84 g/mol)
Correct Answer
A. 5.6 moles
Explanation
Moles will always be a SMALLER number than grams.
So, to calculate: Take the grams DIVIDE by molar mass.
(Hint: Think division generally gives us a smaller number, multiplication generally gives us a larger number).
485.30 grams divided by the molar mass (86.84) = 5.6 moles
7.
How many moles are there in 814.504 g of H_{2}O?
Correct Answer
C. 45.2 moles
Explanation
Moles will always be a SMALLER number than grams.
So, to calculate: Take the grams DIVIDE by molar mass.
(Hint: Think division generally gives us a smaller number, multiplication generally gives us a larger number).
Molar mass of water: Hydrogen 2(1.01) + Oxygen 1 (16.00) = 18.02 g/mol
Divide grams 814.504 g by molar mass (18.02) = 45.2 moles
8.
How many moles of CO_{2} are there in 171.639 g of CO_{2}?
Correct Answer
B. 3.9 moles
Explanation
Moles will always be a SMALLER number than grams.
So, to calculate: Take the grams DIVIDE by molar mass.
(Hint: Think division generally gives us a smaller number, multiplication generally gives us a larger number).
Molar mass of CO2 = Carbon (12.01) + Oxygen 2(16.00) = 44.01 g/mol
Divide grams 171.639 by molar mass (44.01) = 3.9 moles
9.
How many moles of K_{2}O are in 367.38 g of K_{2}O?
Correct Answer
C. 3.9 moles
Explanation
Moles will always be a SMALLER number than grams.
So, to calculate: Take the grams DIVIDE by molar mass.
(Hint: Think division generally gives us a smaller number, multiplication generally gives us a larger number).
Molar mass of K2O = Potassium 2 (39.1) + Oxygen (16.00) = 94.2 g/mol
Divide grams 367.38 by molar mass (94.2 g/mol) = 3.9 moles
10.
How many moles of AlCl_{3} are there in 1,119.972 g?
Correct Answer
A. 8.4 moles
Explanation
Moles will always be a SMALLER number than grams.
So, to calculate: Take the grams DIVIDE by molar mass.
(Hint: Think division generally gives us a smaller number, multiplication generally gives us a larger number).
Molar mass of AlCl3= Aluminum (26.98) + Chlorine 3(35.45) = 133.33 g/mol
Divide the grams 1,119.972 by the molar mass 133.33g/mol = 8.4 moles