A student needs to use a 0.750 mol sample of (NH4)2SO3 for an experiment: a. how many grams does she need to weigh out?
b. how many formula units are in the sample?
To find out the mass of the sample, you need to know the molar mass of (NH4)2SO3.
a. The molar mass of (NH4)2SO3 can be calculated by adding up the atomic masses of the elements in the compound. Let's break it down:
- The atomic mass of nitrogen (N) is 14.01 g/mol.
- The atomic mass of hydrogen (H) is 1.01 g/mol.
- The atomic mass of sulfur (S) is 32.07 g/mol.
- The atomic mass of oxygen (O) is 16.00 g/mol.
Next, calculate the molar mass of (NH4)2SO3:
Molar mass = (2 x atomic mass of N) + (8 x atomic mass of H) + atomic mass of S + (3 x atomic mass of O)
Substitute the values:
Molar mass = (2 x 14.01) + (8 x 1.01) + 32.07 + (3 x 16.00)
Calculate the molar mass to get the answer.
b. To find the number of formula units in the sample, you need to use Avogadro's number, which is 6.022 x 10^23 formula units/mol. First, calculate the number of moles in the sample by dividing the given amount of substance (in this case, 0.750 mol) by the molar mass (which you calculated in part a).
Finally, multiply the number of moles by Avogadro's number to get the number of formula units in the sample.