Answer:
The concentration the student should write down in her lab is 2.2 mol/L
Explanation:
Atomic mass of the elements are:
Na: 22.989 u
S: 32.065 u
O: 15.999 u
Molar mass of sodium thiosulfate, Na2S2O3 = (2*22.989 + 2*32.065 + 3*15.999) g/mol = 158.105 g/mol.
Mass of Na2S2O3 taken = (19.440 - 2.2) g = 17.240 g.
For mole(s) of Na2S2O3 = (mass taken)/(molar mass)
= (17.240 g)/(158.105 g/mol) = 0.1090 mole.
Volume of the solution = 50.29 mL = (50.29 mL)*(1 L)/(1000 mL)
= 0.05029 L.
To find the molar concentration of the sodium thiosulfate solution prepared we use the formula:
= (moles of sodium thiosulfate)/(volume of solution in L)
= (0.1090 mole)/(0.05029 L)
= 2.1674 mol/L
First, we have to calculate the number of moles of H2SO4 in the solution:
V=60 mL = 0.06 L
c=5.85 mol/L
n=V×c=0.06×5.85=0.351 mol
Then we need to find the molar mass of H2SO4:
2×Ar(H) + Ar(S) + 4×Ar(O) =
=2 + 32 + 64 = 98 g/mol
Finally, we need to find the mass of H2SO4:
m=0.351 × 98 = 34.398 g
Answer:
6.2moles of Gold
Explanation:
To solve this problem, we are going to use the mole concept approach.
Given that;
Number of atoms of gold is 3.73 x 10²⁴ atoms
Now;
In 1 mole of any substance, we have 6.02 x 10²³ atoms;
So;
If there 6.02 x 10²³ atoms in 1 mole of any substance;
3.73 x 10²⁴ atoms will contain 
= 6.2moles of Gold
Bestie this subject is scinece.....
