Suppose you want to heat a mug of water (250mL) from room temperature at 25oC to 100oC to make a cup of tea. How much energy (in units of calories and joules) would you need from your microwave? Please make chart!!
Chart?
heat= masswater*specific heat capacity water* change in temp
To calculate the amount of energy needed to heat the water, we can use the formula:
Q = mcΔT,
where Q is the amount of energy transferred, m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature.
Let's break down the calculation:
1. Determine the mass of the water:
Given that the volume (V) of the water is 250 mL, we first need to convert it to mass using the density of water, which is approximately 1 gram/mL:
mass (m) = volume (V) x density (d)
mass (m) = 250 mL x 1 g/mL
= 250 grams
2. Calculate the change in temperature:
ΔT = final temperature (Tf) - initial temperature (Ti)
ΔT = 100°C - 25°C
= 75°C
3. Determine the specific heat capacity of water:
The specific heat capacity (c) of water is approximately 1 calorie/gram °C or 4.184 joules/g °C.
Now, let's calculate the energy (Q) needed in calories and joules:
Energy in calories (cal):
Q = mcΔT
= 250 g x 1 cal/g °C x 75 °C
= 18,750 cal
Energy in joules (J):
To convert from calories to joules, we use the conversion factor 1 cal = 4.184 J.
Q = 18,750 cal x 4.184 J/cal
= 78,435 J
Putting it all together in a chart:
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| Quantity | Value |
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| Mass (m) | 250 grams |
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| ΔT | 75°C |
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| c (cal) | 1 cal/g °C |
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| c (J) | 4.184 J/g °C |
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| Energy (cal) | 18,750 calories |
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| Energy (J) | 78,435 joules |
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