0.12g of rock salt was dissolved in water and titrated with 0.1moldm^-3 silver nitrate until the first permanent brown precipitate of silver chromate is seen. 19.70 cm^3 was required to titrate all the chloride ion. how many moles of chloride ion were titrated? what mass of sodium chloride was titrated? what was the % purity of the rock salt in terms of sodium chloride?

moles Cl⁻ : 0.00197

mass NaCl : 0.115

% purity : 95.83%

Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

Where

M = Molarity

n = Number of moles of solute

V = Volume of solution

So to find the number of moles can be expressed as

n = V x M

Reaction

AgNO₃ + NaCl ⇒ AgCl + NaNO₃

Molarity(concentration) of AgNO₃ = 0.1 mol/dm³(L) = 0.1 M

Volume=V of AgNO₃ = 19.7 ml(cm³)

so mol of AgNO₃ :

.

From the equation, mol ratio AgNO₃ : NaCl  = 1 ; 1, so mol NaCl= mol AgNO₃= 0.00197

NaCl⇒Na⁺+Cl⁻

mol Cl⁻ : mol NaCl = 1 : 1, mol Cl⁻ = 0.00197

beta decay is the answer

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.