A laboratory has a 2.0-mol sample of pure selenium and a 2.0-mol sample of pure chromium. How many more grams of selenium than chromium does this represent?
grams = moles x molar mass
To find out how many more grams of selenium than chromium there are, we need to calculate the difference in their molar masses and then multiply it by the number of moles.
First, let's find the molar mass of selenium (Se) and chromium (Cr). The molar mass is the mass of one mole of a substance, expressed in grams per mole. The molar mass of Se is 78.96 g/mol, and of Cr is 52.00 g/mol.
Next, we calculate the mass of each element. The mass can be obtained by multiplying the number of moles by the molar mass.
For selenium:
Mass of selenium = 2.0 mol * 78.96 g/mol = 157.92 g
For chromium:
Mass of chromium = 2.0 mol * 52.00 g/mol = 104.00 g
Finally, we subtract the mass of chromium from the mass of selenium to find the difference:
Difference = Mass of selenium - Mass of chromium
Difference = 157.92 g - 104.00 g = 53.92 g
Therefore, there are 53.92 grams more of selenium than chromium in the laboratory.