Heat is energy; temperature is how hot something is — and Q = m·c·ΔT links them
Set the mass of water and how much to heat it — c is fixed to water (4200). Watch the heat Q change.
Mass m
Temperature change ΔT
Specific heat c (water) = 4200 J/(kg·°C)
Heat energy needed
84,000 J
Q = m·c·ΔT = 2 × 4200 × 10 = 84,000 J