Calculate the amount of Joules needed to warm water from 21 Celsius to 66 celsius to make a cup of hot cocoa. The cup holds 308 g of water.

This will require

266.9

k

J

of heat energy.

Explanation:

To calculate the energy required to raise the temperature of any given substance, here's what you require:

The mass of the material,

m

The temperature change that occurs,

Δ

T

The specific heat capacity of the material,

c

(which you can look up). This is the amount of heat required to raise 1 gram of that substance by 1°C.

Here is a source of values of c for different substances:

Once you have all that, this is the equation:

Q

=

m

×

c

×

Δ

T

(

Q

is usually used to symbolize that heat required in a case like this.)

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72