contestada

What is the mass in grams of na 2 ​ co 3 ​ (s) (molar mass = 105.98 g/mol) that, when dissolved in 125 ml of water, will make a 0.15 m aqueous solution?

Respuesta :

Molarity is defined as the number of moles of solute dissolved in 1 L of solution. 
molarity of sodium carbonate is 0.15 M
this means that 0.15 moles of sodium carbonate are dissolved in 1 L of solution 
if 1 L contains - 0.15 mol 
then 125 mL should contain - 0.15 mol/L x 0.125 L = 0.019 mol
mass of sodium carbonate in 125 mL - 0.019 mol x 105.98 g/mol = 2.0 g 
2.0 g of sodium carbonate is required to make a 0.15 M solution 
sebassandin

Answer:

[tex]m_{Na_2CO_3}=2.0gNa_2CO_3[/tex]

Explanation:

Hello,

In this case, we consider the equation defining molarity, in order to compute the mass that is present into 125 mL of an aqueous 0.15M of sodium carbonate (solute), Na₂CO₃ as shown below:

[tex]M=\frac{n_{solute}}{V_{solution}}[/tex]

Now, since the unknown is the mass which comes from the moles, by solving for it and subsequently using its molar mass, one obtains:

[tex]m_{Na_2CO_3}=125mL*\frac{1L}{1000mL}*0.15\frac{mol{Na_2CO_3}}{L}*\frac{105.98gNa_2CO_3}{1mol{Na_2CO_3}}   \\m_{Na_2CO_3}=2.0gNa_2CO_3[/tex]

Best regards.

Otras preguntas