Question

The number of moles of KCl in 1000 ml of 3 molar solution is-
A. 1
B. 2
C. 3
D. 1.5

Answer 1

Hint: The mole is defined as the 6.23 × 10^23 numbers of the smallest unit of any substance is called 1 mole of that substance. 1 mole is also equal to the 12 gm of 12C (carbon with atomic mass 12). It is a commonly used scientific unit for the measurement of chemical compounds.

Formula Used:The formula to determine number of moles is –
Molarity (M) = number of moles (n) / Volume (V)
So, the no. of moles will be –
Number of moles (n) = Molarity (M) × Volume (V)
Where volume is calculated in ml.

Complete answer:The number of moles present in one litre of the solution is called molarity. Molarity is also called the molar concentration of a substance. One mole of a substance contains 6.23 × 10^23 units/particles/molecules / atoms / ions of that substance.
In the given question the molarity of KCl is 3 in 1000 ml of solution. Now the number of moles of KCl in the given question is –
Volume in litre, 1 litre (l) = 1000 ml
Number of moles (n) = Molarity (M) × Volume (V)
Number of moles (n) = 3 × 1 (l)
Number of moles (n) = 3 moles
Hence, the moles of KCl in 1000 ml solution is 3.

Thus, Option (C) is correct

Note: When the number of grams equivalent mass of a solute is dissolved in one litre of a solution is called normality. It is denoted by N. Volume, normality, or concentration of any solute can be determined using normality. The concentration of a solute in the solution can be determined with molarity.