How many moles is each of the following?
15.5 g SiO(subscript 2)
0.00688 g AgCl
79.3 g Cl (s.s. 2)
5.96 g KOH
# mols = grams/molar mass
Post your work if you get stuck.
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To find the number of moles for each of the following substances, we need to use the formula:
moles = mass / molar mass
First, we need to determine the molar masses of the substances using the periodic table and adding up the atomic masses of each element in the compound.
1. SiO2 (silicon dioxide):
- Molar mass of Si: 28.0855 g/mol
- Molar mass of O: 15.9994 g/mol
To get the molar mass of SiO2, we multiply the molar mass of Si by 1 (since there's only one Si atom) and the molar mass of O by 2 (since there are two O atoms).
Molar mass of SiO2 = (28.0855 g/mol) + (15.9994 g/mol × 2) = 60.0848 g/mol
Now, we can calculate the number of moles:
moles = 15.5 g / 60.0848 g/mol = 0.258 mol
2. AgCl (silver chloride):
- Molar mass of Ag: 107.8682 g/mol
- Molar mass of Cl: 35.453 g/mol
Molar mass of AgCl = (107.8682 g/mol) + (35.453 g/mol) = 143.3212 g/mol
Calculating the number of moles:
moles = 0.00688 g / 143.3212 g/mol = 4.801 × 10^-5 mol
3. Cl2 (chlorine gas):
- Molar mass of Cl: 35.453 g/mol
Molar mass of Cl2 = 35.453 g/mol × 2 = 70.906 g/mol
Finding the number of moles:
moles = 79.3 g / 70.906 g/mol = 1.117 mol
4. KOH (potassium hydroxide):
- Molar mass of K: 39.0983 g/mol
- Molar mass of O: 15.9994 g/mol
- Molar mass of H: 1.0079 g/mol
Molar mass of KOH = (39.0983 g/mol) + (15.9994 g/mol) + (1.0079 g/mol) = 56.1056 g/mol
Determining the number of moles:
moles = 5.96 g / 56.1056 g/mol = 0.106 mol
Therefore, the number of moles are as follows:
- 15.5 g SiO2 = 0.258 mol
- 0.00688 g AgCl = 4.801 × 10^-5 mol
- 79.3 g Cl2 = 1.117 mol
- 5.96 g KOH = 0.106 mol