1. Calculate the amount of heat, in kJ, that is transferred to 45.7 mL of water when its temperature changes from 23.6 °C to 41.3 °C. The density of water is 1.00 g/mL and the specific heat of water is 4.184 J/(g•°C). 2. Should the sign of the heat transferred in the question above be positive or negative?

from

H=mc∆T

where by;

H is amount of heat.

m is mass of water.

c is specific heat of water.

∆T is change in temperature.

m=density ×volume

m=1.00g/ml×45.7ml

m=45.7g

∆T=Tt-T°

∆T=41.3°C-23.6°C

∆T=17.7°C

H=45.7g×4.184j(g•°C)×17.7°C

H=3,384.396J

H=3,384.396÷1000

H=3.384kJ

Explanation:

H=mc∆T

where by;

H is amount of heat.

m is mass of water.

c is specific heat of water.

∆T is change in temperature

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e