Use the molar mass of the following in order to calculate the number of moles from the given masses. Watch the significant figures
a) 0.025 g of oxygen
b)0.657 g og copper
c) 0.7 g of chlorine
I know how to calculate with finding the molar mass but not this way. thank you so much
I'm thinking you would take 0.025 x 16.00 and that will equal ...
mols = grams/molar mass.
a. 0.025/32 = ?
To calculate the number of moles from the given masses, you need to use the molar mass of each element. The molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol).
a) Oxygen (O):
The molar mass of oxygen is approximately 16.00 g/mol. To find the number of moles, you can divide the given mass (0.025 g) by the molar mass:
0.025 g / 16.00 g/mol = 0.0016 mol
b) Copper (Cu):
The molar mass of copper is approximately 63.55 g/mol. Dividing the given mass (0.657 g) by the molar mass will give you the number of moles:
0.657 g / 63.55 g/mol = 0.0103 mol
c) Chlorine (Cl):
The molar mass of chlorine is approximately 35.45 g/mol. Similarly, divide the given mass (0.7 g) by the molar mass to get the number of moles:
0.7 g / 35.45 g/mol = 0.020 mol
Now, let's consider significant figures. When performing calculations, the number of significant figures in your result should match the least precise measurement you started with. In this case, the given masses have three significant figures. Thus, your final answers should each have three significant figures:
a) 0.025 g of oxygen = 0.0016 mol (three significant figures)
b) 0.657 g of copper = 0.0103 mol (also three significant figures)
c) 0.7 g of chlorine = 0.020 mol (three significant figures)
Remember to match the number of significant figures in your final answer to the least precise measurement given in the question.