Multiple Choice
A compound has an empirical formula of CH\(_2\) and a molar mass of 30.069 g/mol. What is its molecular formula?
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3. Chemical Reactions
Molecular Formula
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How many atoms of oxygen are present in 2Ca(NO3)2?
A
6
B
4
C
8
D
12
Verified step by step guidance1
Identify the chemical formula given: 2Ca(NO3)2. This means you have 2 formula units of calcium nitrate.
Focus on the nitrate ion part, NO3. Each nitrate ion contains 3 oxygen atoms.
In the formula Ca(NO3)2, there are 2 nitrate ions per formula unit, so multiply the number of oxygen atoms in one nitrate ion by 2: 3 oxygen atoms × 2 = 6 oxygen atoms per formula unit.
Since there are 2 formula units of Ca(NO3)2, multiply the oxygen atoms per formula unit by 2: 6 oxygen atoms × 2 = 12 oxygen atoms total.
Therefore, the total number of oxygen atoms in 2Ca(NO3)2 is 12.
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