Correct Answer - Option 2 : X is more concentrated than Y
Explanation -
- To compare the concentrations of caustic soda in bottles X and Y, we first have to convert them into the same unit of concentration.
- So we will be converting the concentration of 1 molar to molality.
- In bottle X, 1 Molar or 1M means 1 mol of NaOH in 1000ml of water.
- So, we can say that 1 mol of NaOH is present in 1000g of the solution because density is 1gm/ml.
- In 1000g of solution, the mass of NaOH is = 40g
- 1 mol of NaOH is in (1000 - 40g = 960g) of water
- Hence, Molality of NaOH in X is equal to 91/960) X 1000 = 1.041
- 1.041 > 1, Concentration in bottle X is more than bottle Y.
Thus, the concentration of 1 molar NaOH is greater than 1 molal of NaOH.
The correct answer to this question is - X is more concentrated than Y.
There are three units of concentration in chemistry:
1. Molarity -
- The amount of moles of solute per litre of solution is known as molarity (M).
- Molarity is defined as the number of moles of solute per litre of solution.
- Sulphuric acid, for example, has a molecular mass of 98. If 98 grammes of sulphuric acid are present in 1 litre of solution, the solution is called a molar solution of sulphuric acid. As a result, the molarity will be 1.
2. Molality -
- The amount of moles of solute per kilogramme of solvent is known as molality (m).
- Molality is defined as the number of moles of solute per kilogramme of solvent.
- It is 1 molal solution of sulphuric acid in water if 98 gramme of sulphuric acid is present in 1 kilogramme of water. As a result, molality will be 1.
3. Normailtiy -
- The number of equivalents per litre of solution is defined as normality:
- Number of equivalents /1 L of solution = normality
- Because only one mole of H+ is generated per mole of HCl, a 1 N HCl solution equals a one molar HCl solution.
- However, because 2 moles of H+ are generated per mole of acid in sulphuric acid H2SO4, 1 mol H2SO4 = 2N H2SO4.
