Question

A platinum resistance thermometer has resistances of 200.0 V when placed in a 0°C ice bath and 253.8 V when immersed in a crucible containing melting potassium. What is the melting point of potassium? Hint: First determine the resistance of the platinum resistance thermometer at room temperature, 20.0°C.

Answer 1

To find the melting point of potassium, we can use the relationship between resistance and temperature. First, determine the resistance of the platinum resistance thermometer at room temperature. Then, calculate the change in resistance and use it to find the change in temperature. Finally, add the change in temperature to the initial temperature of the ice bath to find the melting point of potassium.

Step-by-step explanation:

To find the melting point of potassium, we can use the relationship between resistance and temperature. First, we need to determine the resistance of the platinum resistance thermometer at room temperature, 20.0°C. We can use the resistances of the thermometer in the ice bath and when immersed in the crucible containing melting potassium to calculate the change in resistance (ΔR). Then, we can use the change in resistance per degree Celsius (α) for the platinum resistance thermometer to calculate the change in temperature (ΔT). Finally, we can add the change in temperature to the initial temperature of the ice bath (0°C) to find the melting point of potassium.

Let's calculate the change in resistance (ΔR) first:

ΔR = 253.8 V - 200.0 V

Next, we need to determine the change in temperature (ΔT) using the change in resistance:

ΔT = ΔR / α

Finally, we can find the melting point of potassium by adding the change in temperature to the initial temperature of the ice bath:

Melting point of potassium = 0°C + ΔT

Answer 2

Answer: 63.26°c

Step-by-step explanation:

We first find the resistance at room temperature Ro, once this is found, we plug in the Ro, value into our normal equation to obtain the temperature at which the potassium melts. We must know the value of the temperature coefficient of resistance (alpha) which I have provided in the solution.