WorksheetsECA Review
Total questions: 12
Worksheet time: 6mins
Name
Class
Date
1.
Calculate the number of moles in 2.46 × 10²¹ molecules of CO₂.
a)
1.66 × 10⁻²⁰
b)
4.09 × 10⁻³
c)
2.00 × 10⁴
d)
1.45 × 10⁹
2.
Calculate the molar mass of (NH₄)₂C₂O₄. .
a)
100.00 g/mol
b)
124.10 g/mol
c)
240.78 g/mol
d)
316.20 g/mol
3.
A gaseous hydrocarbon has a density of 2.59 g/L at STP. What is the identity of the hydrocarbon?
a)
Butane, C₄H₁₀
b)
Ethane, C₂H₆
c)
Methane, CH₄
d)
Propane, C₃H₈
4.
What is the percent composition of PbO₂?
a)
50% Pb, 50% O₂
b)
86.6% Pb, 13.4% O₂
c)
43.4% Pb, 56.6% O₂
d)
33.3% Pb, 66.7% O₂
5.
A compound is analyzed and found to have the percent composition shown in the pie chart. What is the empirical formula for this compound?
a)
Na₂S₂O₃
b)
Na₂S₃O₂
c)
Na₁SO₄
d)
Na₂SO₂
6.
What is the molarity when 4.24 mol of NaCl is prepared in 2.00 L of solution?
a)
1.06 M
b)
2.12 M
c)
4.24 M
d)
8.48 M
7.
What is the molarity of a solution that contains 78.5 g of copper(II) chloride in 1.50 L of solution?
a)
52.3 M
b)
0.390 M
c)
1.14 M
d)
0.585 M
8.
What is the density of carbon monoxide gas at STP conditions?
a)
0.800 g/L
b)
1.25 g/L
c)
22.4 g/L
d)
28.0 g/L
9.
It states that every sample of the same substance contains identical elements in the same fixed ratio by mass.
a)
Avogadro's Law
b)
Law of Conservation of Mass
c)
Law of Definite Proportion
d)
Boyle's Law
10.
A lab technician knows the empirical formula of a molecule is CH₂. He uses a mass spectrometer to determine the molar mass of the compound. The test results show that the molar mass is 56.1 g/mol. What is its molecular formula?
a)
CH₂
b)
C₂H₄
c)
C₃H₆
d)
C₄H₈
11.
Molarity is defined as the _________ per _________. A solution with lower amounts of solute is called a _________ solution, while a solution with higher amounts is called a ____________ solution.
a)
moles of solute, liters of solution, diluted, concentrated
b)
grams of solute, liters of solution, concentrated, diluted
c)
liters of solution, moles of solute, diluted, concentrated
d)
concentrated, diluted, moles of solute, liters of solution
12.
How many moles of sulfuric acid
would be needed to create 8.5 liters of acidic
solution with a molarity of 3.0 M
a)
18.5 mol
b)
20.2 mol
c)
25.5 mol
d)
13.5 mol
100 %
