Calculate the number of moles of sugar in 800 ml of a 2.6 M solution

2.08moles

Explanation:

Given parameters:

Volume of solution = 800mL   = 0.8L

Molarity  = 2.6M

Unknown:

Number of moles of sugar in the solution = ?

Solution:

We need to understand the relationship between number of moles, volume and molarity of a solution.

The molarity of a solution is the number of moles of solute of a substance dissolved in a given solvent.

         Molarity  =

   Number of moles of solute  = molarity x volume of solution

Now input the parameters and solve;

            Number of mole of solute  = 2.6 x 0.8  = 2.08moles

The number of moles of sugar is 2.08moles

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol