Molarity (M) = moles of the solute (mol) / Volume of the solution (L)
The molarity of the given KCl solution = 2.10 M
Volume of the given KCl solution = 85.0 mL
Hence,
2.10 M = Moles of KCl / 85.0 x 10⁻³ L
Moles of KCl = 2.10 M x 85.0 x 10⁻³ L
= 0.1785 mol
Moles (mol) = Mass (g) / Molar mass (g mol⁻¹)
Molar mass of KCl = 74.56 g mol⁻¹
Hence,
0.1785 mol = Mass of KCl / 74.56 g mol⁻¹
Mass of KCl = 0.1785 mol x 74.56 g mol⁻¹
= 13.30 g
Hence, mass of given KCl in 85.0 mL is 13.30 g.
4.5 x 10-4
An easy trick is to count the zeros.
John Dalton in d year 1808 proposed d atomic theory..
1.All elements are made up of small, indivisble particles called atoms.
2.Atoms can neither be created nor destroyed.
3.Atoms of d same element are alike in every aspect, &differ from atoms of all other elements.
4. When atoms combine with other atoms, they do so in simple ratios.
Answer:
Na₂CO₃ · 10H₂O
Explanation:
The formula for sodium carbonate hydrate is:
Na₂CO₃ · xH₂O
The unknown "x" is the number of water molecules contained in the hydrate.
To find "x" we have to use the hydrogen percentage in the sample, 7.05 % H.
First we calculate the molecular weight of Na₂CO₃ · xH₂O:
molecular weight of Na₂CO₃ · xH₂O = 23 × 2 + 12 + 16 × 3 + 18x
molecular weight of Na₂CO₃ · xH₂O = 106 + 18x g/mole
Now we devise the fallowing reasoning tanking in account 1 mole of Na₂CO₃ · xH₂O:
if in 106 + 18x grams of Na₂CO₃ · xH₂O we have 2x grams of hydrogen
then in 100 grams of Na₂CO₃ · xH₂O we have 7.05 grams of hydrogen
106 + 18x = (100 × 2x) / 7.05
106 + 18x = 28.4x
106 = 28.4x - 18x
106 = 10.4x
x = 106 / 10.4
x = 10.2 ≈ 10
The formula for the washing soda is Na₂CO₃ · 10H₂O.
Answer:
Equation 2, because K being more reactive, exchanges position with Pb in PbNO3.
Explanation:
