How many joules are needed to heat 2.0 L of water from 20°C to 100°C?

To determine how many joules are needed to heat 2.0 L of water from 20°C to 100°C, we can use the formula for heat energy:

[ q = mc\Delta T ]

Where:

• ( q ) is the heat energy (in joules)
• ( m ) is the mass of the water (in grams)
• ( c ) is the specific heat capacity of water (approximately 4.18 J/g°C)
• ( \Delta T ) is the change in temperature (in °C)

1. First, convert the volume of water to mass. Since the density of water is about 1 g/mL, 2.0 L of water is equivalent to 2000 g.

2. Next, calculate the change in temperature (( \Delta T )): [ \Delta T = 100°C - 20°C = 80°C ]

3. Now, substitute the values into the heat energy formula: [ q = (2000 , \text{g}) \times (4.18 , \text{J/g°C}) \times (80°C) ]

4. Performing the