Multiple Choice
What is the total mass, in grams, of 3.01 × 10^{23} atoms of helium gas (He)?
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2. Atoms & Elements
Calculating Molar Mass
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What is the molar mass of (NH_4)_2SO_4?
A
116.17 amu
B
132.17 amu
C
114.12 amu
D
96.07 amu
Verified step by step guidance1
Identify the chemical formula of the compound: (NH_4)_2SO_4, which is ammonium sulfate.
Determine the number of each type of atom in the formula: 2 ammonium ions (NH_4) each containing 1 nitrogen (N) and 4 hydrogens (H), plus 1 sulfate ion (SO_4) containing 1 sulfur (S) and 4 oxygens (O). So total atoms are: N = 2, H = 8, S = 1, O = 4.
Find the atomic masses of each element from the periodic table: N ≈ 14.01 amu, H ≈ 1.008 amu, S ≈ 32.07 amu, O ≈ 16.00 amu.
Calculate the total mass contributed by each element by multiplying the number of atoms by their atomic masses: For example, total N mass = 2 × 14.01 amu, total H mass = 8 × 1.008 amu, and so on.
Sum all the individual masses to get the molar mass of (NH_4)_2SO_4: Molar mass = (mass of N) + (mass of H) + (mass of S) + (mass of O).
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