Question

a solution of sodium hydroxide is made by dissolving 22.5g of salt in 500ml of the solution. find the concentration of solution in g/dm3 and mol/dm3​

Answer 1

Number of moles of Na2co3=

$22.5 \div 106 = 0.21moles$

Molarity of solution= 0.21/0.5=0.42 mil/litre

Na2co3 =>(2Na)^+ + (Co3)^ 2-

concentration of (Co3)^ 2- = 0.42M

concentration of Na+ = 2 x 0.42=0.84

Answer 2

Answer:

45.0 g/dm³ and 1.13 mol/dm³

Explanation:

In g/$dm^{3}$:

There are 1000mL in 1$dm^{3}$. Use this conversion factor to convert 500mL to $dm^{3}$:

(500mL)($\frac{1dm^{3} }{1000mL}$)=0.500$dm^{3}$

Therefore, 22.5g/500mL=22.5g/0.500$dm^{3}$=45.0g/$dm^{3}$

In mol/$dm^{3}$:

Calculate the gram formula mass (GFM) of sodium hydroxide (NaOH) by adding up the formula masses of each individual atom:

(22.99g+16.00g+1.008g)/mol=39.998g/mol

$(\frac{45.0g}{dm^{3} } )(\frac{1mol}{39.998g} )=1.13mol/dm^{3}$