Suppose you wanted to heat a mug of water (250 ml) from room temperature 25 c to 100 c to make a cup of tea. how much energy (in units of calories and joules) would you need from your microwave?

The amount of heat needed by the microwave is 18750 Cal or 78450 J

Explanation:

To calculate the mass of water, we use the equation:

Density of water = 1 g/mL

Volume of water = 250 mL

Putting values in above equation, we get:

To calculate the amount of heat absorbed, we use the equation:

where,

m = mass of water = 250 g

c = specific heat capacity of water = 1 Cal/g°C

= change in temperature =

Putting values in above equation, we get:

Converting the amount of heat absorbed in Joules, we use the conversion factor:

1 Cal = 4.184 J

So,

Hence, the amount of heat needed by the microwave is 18750 Cal or 78450 J