a. Moles of gold = 35.12/197 = 0.18 moles. b. number of gold molecules = moles x 6.02 x 10^23 = 0.18 x 6.02 x 10^23= 1.08 x 10^23
Since it's C2, then it must be two Carbon atoms. Think of it this way; there are two atoms of Hydrogen in a water molecule, so we now have H2O.
Answer:
38.9%
Explanation:
below, determine the mass percent of Fe3+ in a 0.6450 g sample of iron ore, if 22.40 mL of a 0.1000 M stannous chloride, SnCl2(aq), solution is required to completely react with the Fe3+ present in the ore sample. The chemical equation for the reaction is
2 Fe3+ (aq) + Sn2+ (aq) →2Fe2+ (aq) + Snº+(aq).
O 19.40%
O 6.196%
O 38.79%
O 9.697%
2 Fe3+ (aq) + Sn2+ (aq) →2Fe2+ (aq) + Snº+(aq).ole of Sn2+
for every mole of Sn2+, tere are 2 moles of Fe3+
- 22.4/1000L of 0.1000 M Sn2+ = 22.4 X 0.10/1000 = 0.00224 mole
so there are 0.00224 X 2= 0.00448 moles Fe3+
iron atomic mass is 56
56 X 0.00448 = 0.251 gm Fe3+
so the mass % of the Fe3+ in the 0.645 gm iron ore sample is
(0.251/0.645) X 100 = 38.9%
Answer:
0.091 mol/L
Explanation:
Molarity of a substance , is the number of moles present in a liter of solution .
M = n / V
M = molarity ( unit = mol / L or M )
V = volume of solution in liter ( unit = L ),
n = moles of solute ( unit = mol ),
Moles is denoted by given mass divided by the molecular mass ,
Hence ,
n = w / m
n = moles ,
w = given mass ,
m = molecular mass .
From the data of the question , it is given that ,
w = 1.5 g
V = 220 mL
Since ,
1 mL = 1/1000L
V = 0.220 L
As we known , the mass of bleach NaOCl is ,
m = 74.44 g/mol
from the above equation , moles can be calculated as -
n = w / m
n = 1.5g / 74.44 g/mol
n = 0.0201 mol
Molarity of the solution is calculated as ,
M = n / V
M = 0.0201 mol / 0.220 L
M = 0.091 mol/L
