How many joules are needed to change the temperature of 40 g of water from 33 C to 23 C?

Explanation:

Given parameters:

Mass of water  = 40g

Initial temperature  = 33°C

Final temperature  = 23°C

Specific heat capacity of water  = 4.2J/g°C

Unknown:

Quantity of heat = ?

Solution:

To solve this problem, we use the expression below;

       H  = m c Δt

H is the quantity of heat

m is the mass

c is the specific heat capacity

Δt is the change in temperature

      H  = 40 x 4.2 x (23 - 33) = -1680J

The water will have to lose 1680J of heat to bring it to that final temperature.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.