Question

a student adds 3.5 moles of solute to enough water to make a 1500mL solution. what is the concentration?

Answer 1

Hey there!:

Molarity, molar concentration, concentration in mol/L or concentration in quantity of matter is the ratio of the amount of matter of the solute (mol) by the solution volume (in liters), expressed in the Unit mol/L (molar).

Number of moles  = 3.5 moles

1 L = 1000 mL

Volume in liters  = 1500 mL / 1000 =>  1.5 L

Therefore:

Molarity = number of moles / Volume in liters:

Molarity = 3.5 / 1.5

Molarity =  2.333 M

Hope this helps!

Answer 2

Hello!

The answer is:

$MolarConcentration=\frac{3.5moles}{volume(1.5L)}=2.33molar$

Why?

Since there is not information about the solute but only its mass, we need to assume that we are calculating the molar concentration of a solution or molarity. So, need to use the following formula:

$MolarConcentration=\frac{mass(solute)}{volume(solution)}$

Now, we know that the mass of the solute is equal  3.5 moles and the volume is equal to 1500 mL or 1.5L

Then, substituting into the equation, we have:

$MolarConcentration=\frac{3.5moles}{1.5L}=2.33molar$

Have a nice day!