(Please Help) Determination of boiling point of unknown liquid

Question

Data:

Calibration of thermometer:

In ice-water system:

Actual temperature, T(°C): T₁: 0.0

Thermometer reading, R(°C): R₁ :0.2

In boiling water system:

Actual temperature, T(°C): T₂: 100.0

Thermometer reading, R(°C): R₂ :100.0

Atmospheric pressure of the day: 760.5 mmHg

Measurement of boiling point of unknown liquid:

Thermometer reading, R(°C):

Trial 1: 82.0

Trial 2: 83.0

Average(R₃): 82.5

Calculations

Assume a linear relationship between T and R. Construct a straight line that can pass through the two data points.

1. Slope of the straight line (m): ________
2. Since (T-T₁/R-R₁)=m, express T in terms of R:

T=

By substituting the average value of thermometer reading of boiling unknown liquid (R₃) into equation obtained above, the accurate boiling point of the unknown could be found:

Boiling point of unknown =______________°C

Answer 1

There is some slight difference between your thermometer readings (R) and the actual temperature readings (T). We need to generate an equation that will relate R to T so that we can determine actual temperatures from the readings.

We are told that this equation must be a straight line. The formula for a strainght line is y=mx+b. where b and m are constants and m is the slope of the line.

We can substitute T for y and R for X, thus T=mR+b

Now we can plug in your two datapoints at (T=0, R=.2) and (T=100, R=100.)

This should allow us to solve for b and m. T is very close to R at both datapoints so R shold be very close to 1 and b should be close to 0.

Now, plugging in your measured readings for R in this equation should allow us to calculate T.