NH3 is neutralised by the equation:
HCL + NH3 -> NH4CL
In this equation there is a one to one relationship in terms of the number of moles of each reactant. I.e. To neutralise 1 mole of NH3 we require 1 mole of HCL.
To calculate the concentration of NH3 required, we must first calculate the number of moles of HCL used.
volume HCL = 35.5mL = 0.0355 litres
concentration HCL = 0.23M = 0.23 mole/litre
Note that the term "M" for concentration simply means moles/litre
number moles = concentration x volume
number moles HCL = 0.0355 x 0.23 = 0.008165 moles HCL
based on the equation, we know the number of moles of NH3 must be the same
So,
moles NH3, n = 0.008165
volume NH3, v = 20.0mL = 0.020 litres
n = c x v
c = n / v
c = 0.008165 / 0.020
=0.41
i.e. the concentration of NH3 would be 0.41 moles/litre or 0.41M
This intuitively makes sense because there is less volume of NH3 required to be neturalised, in a one-to-one mole relationship. So the concentration of NH3 would need to be higher than that of HCL.
The freezing point would be 3.72 *C
Answer:
Increasing precision with multiple measurements
Explanation:
The more measurements you take (provided there is no problem with the clock!), the better your estimate will be. Taking multiple measurements also allows you to better estimate the uncertainty in your measurements by checking how reproducible the measurements are.
