Stoichiometry helpppp

Question

How many moles of calcium are in 3.24x10²³ atoms of calcium? Round to 2 decimal places for your answer.

  __ mol Ca?

What mass of lead is 0.294 mol of lead? Round to 2 decimal places for your answer.

 ___  g Pb?

i need work to show

Answer 1

To determine the numbers of moles in any amount of anything, first you need to know how many molecules are in 1 mole: 6.02 x 10²³.

You have 3.24x10²³ atoms of calcium. To figure out how many moles that is, first you need to figure out how many atoms of Calcium there are per molecule. Since Calcium is a monoatomic element, there is 1 molecule of Calcium per calcium atom. Next, let's set up the equation:

3.24x10²³ atoms of calcium x (1 molecule/1atom) x (1 mole/6.02 x 10²³ molecules)

Simplified, that's (3.24 x 10²³) divided by (6.02 x 10²³)

Rounded to two decimal places, that's .53 moles.

To answer the second question, we first need to determine how many grams there are in 1 mole of lead. To do so, we consult the periodic table and find the atomic mass of Pb. The atomic mass of Pb is 207.2 grams per mole. Now let's set up the equation:

.294 mol Pb x (207.2 grams/1 mole) = .294 x 207.2 = 60.92 g Pb.