Chem homework please help

Question

Calculate the mass, in grams, of  mol of xenon, .

Calculate the mass, in grams, of  mol of carbon dioxide, .

Answer 1

To solve questions like this, you have to remember that one mole of the substance can be calculated using the periodic table.

The molecular mass of Xe is 131. This means, by definition, that one mole of Xe is 131 g. Now it's a matter of arithmetic: if 1 mole of Xe is 131 g, what is the weight of 4.15 mol of Xe? That will be 4.15*131 g = 543.65 g.

The same goes for CO₂. The mass of 1 mole of CO₂ = 1 mole of C + 2 moles of O = 12 + 2(16) = 12 + 32 = 44 g. If 1 mole of CO₂ weighs 44 g, then the mole of 0.787 mole of CO₂ is 0.787*44 = 34.63 g.

The key concepts here are: the molar mass for a substance can be calculated using molecular masses from the periodic table. Always calculate the weight of one mole, then multiply with the amount the question stem is asking for.

Hope this helps!