You have a 2.00 kg block of lead. Lead melts at 327.5°C. CPb = 130.0 , and ï�„Hf for lead is 2.04 × 104 J/kg. Say you start at room temperature (25.0°C). How much heat must you transfer to melt all the lead?
heat= heataddedToIncreaseTemp+ heataddedToMelt
= 2kg*CPb*(327.5-25)+2kg*Hf
327.5x25.0=302.5 T= 302.5C q=2.00kg(130.0 kqc) (302.5c) q=H&M
Q=78,650J Q=2.04x10^4 j/kg (2.00g)=40,800J
Q=119,450J „³ 119,000J
To calculate the heat required to melt all the lead, you can use the formula:
Q = m * �Hf
Where:
Q is the heat required
m is the mass of the lead (2.00 kg)
ï�„Hf is the heat of fusion for lead (2.04 × 10^4 J/kg)
Calculating Q:
Q = 2.00 kg * 2.04 × 10^4 J/kg
Q = 40,800 J
Therefore, you must transfer 40,800 J of heat to melt all the lead.
To find out how much heat must be transferred to melt all the lead, we need to calculate the heat required to raise the temperature of the lead from its initial temperature of 25.0°C to its melting point of 327.5°C, as well as the heat required to melt the lead.
Let's break down the calculation step by step:
Step 1: Calculate the heat required to raise the temperature of the lead from 25.0°C to its melting point of 327.5°C.
The formula to calculate the heat required to raise the temperature of a substance is:
Q1 = m * Cp * ΔT
Where:
Q1 is the heat required
m is the mass of the substance (2.00 kg)
Cp is the specific heat capacity of the substance (130.0 J/kg°C)
ΔT is the change in temperature (327.5°C - 25.0°C)
Plugging in the values:
Q1 = 2.00 kg * 130.0 J/kg°C * (327.5°C - 25.0°C)
Step 2: Calculate the heat required to melt the lead.
The formula to calculate the heat required to melt a substance is:
Q2 = m * ΔHf
Where:
Q2 is the heat required
m is the mass of the substance (2.00 kg)
ΔHf is the heat of fusion for the substance (2.04 × 10^4 J/kg)
Plugging in the values:
Q2 = 2.00 kg * 2.04 × 10^4 J/kg
Step 3: Add both quantities of heat together to obtain the total heat required:
Total heat required = Q1 + Q2
Calculating Q1:
Q1 = 2.00 kg * 130.0 J/kg°C * (327.5°C - 25.0°C)
Q1 = 2.00 kg * 130.0 J/kg°C * 302.5°C
Calculating Q2:
Q2 = 2.00 kg * 2.04 × 10^4 J/kg
Adding Q1 and Q2:
Total heat required = Q1 + Q2
Finally, perform the calculations to get the total heat required.