1. how many moles are in 3.4 x 1024 molecules of hcl?
2. how many grams are in 2.59 x 1023 formula units of al2o3?
3. how many grams are in 9.05 x 1023 atoms of silicon?
4. if you had 7.00 moles of pto2, how many grams would you have?
5. how many moles are in 29.2 l of oxygen gas at stp?
6. what is the volume (liters) of 75.8 g of n2 at stp?
show work for each one .

1. How many moles are in 3.4 x 10²⁴ molecules of HCl?

if there are 6.022 × 10²³ molecules in 1 mole of HCl

then there are 3.4 × 10²⁴ molecules in X moles of HCl

X = (3.4 x 10²⁴ × 1) / 6.022 × 10²³ = 5.6 moles of HCl

2. How many grams are in 2.59 x 10²³ formula units of Al₂O₃?

 if there are 6.022 × 10²³ units in 1 mole of Al₂O₃

then there are 2.59 × 10²³ units in X moles of Al₂O₃

X = (2.59 x 10²³ × 1) / 6.022 × 10²³ = 0.43 moles of Al₂O₃

number of moles = mass / molecular weight

mass = number of moles × molecular weight

mass of Al₂O₃ = 0.43 × 102 = 43.86 g

3. How many grams are in 9.05 x 1023 atoms of silicon?

if there are 6.022 × 10²³ atoms in 1 mole of silicon

then there are 9.05 × 10²³ atoms in X moles of silicon

X = (9.05 x 10²³ × 1) / 6.022 × 10²³ = 1.5 moles of silicon

mass = number of moles × molecular weight

mass of silicon = 1.5 × 28 = 42 g

4. If you had 7.00 moles of PtO₂, how many grams would you have?

mass = number of moles × molecular weight

mass of PtO₂ = 7 × 227 = 1589 g

5.How many moles are in 29.2 L of oxygen gas at STP?

At standard temperature and pressure (STP) we may use the  following formula:

number of moles = volume (L) / 22.4 (L / mol)

number of moles of oxygen = 29.2 / 22.4 = 1.3

6. What is the volume (liters) of 75.8 g of N₂ at STP?

number of moles = mass / molecular weight

number of moles of N₂ = 75.8 / 28 = 2.7 moles

At standard temperature and pressure (STP) we may use the  following formula:

number of moles = volume (L) / 22.4 (L / mol)

volume = number of moles × 22.4

volume of N₂ = 2.7 × 22.4 = 60.48 L