The molarity of a solution prepared by dissolving 141.6g of citric acid in water is calculated as below
find the the number of moles
moles= mass/molar mass
= 141.6 g/ 192 g/mol = 0.738 moles
molarity= moles/molar mass
= 0.738/3500 x1000 = 0.21 M
Answer:
Na₂CO₃.2H₂O
Explanation:
For the hydrated compound, let us denote is by Na₂CO₃.xH₂O
The unknown is the value of x which is the amount of water of crystallisation.
Given values:
Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g
Mass after heating (Na₂CO₃) = 3.22g
Mass of the water of crystallisation = (4.31-3.22)g = 1.09g
To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:
Number of moles = 
Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹
Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹
Number of moles of Na₂CO₃ =
= 0.03mole
Number of moles of H₂O =
= 0.06mole
From the obtained number of moles:
Na₂CO₃ H₂O
0.03 0.06
Simplest
Ratio 0.03/0.03 0.03/0.06
1 2
Therefore, x = 2
Tin is classified as a metal in family 14.
The magnetic field is believed to be generated by electric currents in the conductive material of its core, created by convection currents due to heat escaping from the core. So your answer is A
A set of attainable values for some physical quantity such as energy or wavelength