Question #08917

1 Answer
Feb 4, 2017

1
0.3 * 1.204 * 10^24 = 3.612 * 10^23 H atoms
0.7 * 1.204 * 10^24 = 8.428 * 10^23 atoms of unknown element

2
3.612 * 10^23 H atoms * 1/(6.022 * 10^23) mol/atoms * 1.01/1 g/mol = 0.606g

So, 57.14 - 0.606 = 56.53g

3
8.428 * 10^23 * 1/(6.022 * 10^23) = 1.3995 mol of unknown element

Molar mass = 56.53/1.3995 = 40.3 gmol

With slight error, this is the molar mass of argon on the periodic table (i.e 39.95 g/mol).