<span> an analytical method used to separate colored chemicals or substances.</span>
2Na(s) + 2 H2O (liquid) -> 2 NaOH (aq) + H2 (g)
1) 2 reactants are given, so we have to find which of them is an excess reactant and which of them will react completely.
Convert gram of Na and H2O into moles.
M(Na) =23.0 g/mol
10.0 g Na*1 mol Na/23.0 g Na≈0.4349 mol Na
M(H2O) = 2*1.0 +16.0 = 18.0 g/mol
50.0 g H2O*1 mol H2O/18.0 g H2O =2.778 mol H2O
2Na(s) + 2 H2O (liquid) -> 2 NaOH (aq) + H2 (g)
from equation 2 mol 2 mol
given 0.4349 mol 2.778 mol
We can see that H2O is an excess reactant, so we are going to find amount of H2 using Na.
2)
2Na(s) + 2 H2O (liquid) -> 2 NaOH (aq) + H2 (g)
from equation 2 mol 1 mol
given 0.4349 mol x mol
x=(0.4349*1)/2 =0.21745 mol H2
3) mass of H2
0.21745 mol H2 * 2.0 g H2/1 mol ≈ 0.435 g H2
Answer : 0.435 g H2.
D) burning magnesium ribbon, as combustion is a chemical reaction so causes chemical change. The other 3 options do not involve reactions so there isn't a chemical change.
<u>The </u><u>emperical formula </u><u>can be </u><u>calculated </u><u>as follows:</u>
<u>mass :</u> 4.12g of N and 0.88g of H
<u>moles:</u> 4.12g/14.007 and 0.88g/1.008
<u>moles:</u> 0.294 and 0.873
<u>moles/smallest number</u>: (gives the ratio of atoms)
0.294/0.294 and 0.873/0.294
1 and 2.969
1 and 3
The simplest ratio of N : H is 1 : 3
<u>Hence the </u><u>emperical formula </u><u>is </u><u>NH3</u>
<u>Explanation:</u>
1. The emperical formula can be found by getting the <u>simplest ratio of atoms in a molecule.</u>
2. To get the simplest ratio of atoms we find out the <u>number of moles of each atoms in it.</u>
3. From the number of moles of atoms we can find the simplest ratio of each atom by dividing the <u>number of moles by the smallest number.</u>