Question

Explain what effect, if any, the following experimental problems would be expected to have on the measure values of the molar heats of neutralization.

a. More than 45 mL of acid solution is used.

b. Less than 45 mL of acid solution is used.

c. Some of the heat absorbed by the cup is transferred to the desk.

d. The amount of heat absorbed by the thermometer is not small.

e. The heat capacity of the solution is lower than the heat capacity of water. f. The density of the acid solutions are greater than 1.00 g/mL.

Answer 1

a)

if there is more mass, then Tfinal will not be high enough , since there is much more mass

then

HRxn will be lowered

b)

not all species react, then this is not 100%

HRxn will be lower

c)

This assumes adiabatic, i.e. no heat loss

if heat is lost by desk, then heat of reaction will be lower, since the syste will not achieve its Temperature

d)

similar as in C;

the adiabatic system fails, so HRxn lowers

e)

if Cp is lower, then Tfinal increases, since it requires less heat to increase T

the HRxn will be higher than the real value

f)

if density is higher, this implies more mass per volume

so this will have a lowe rHRxn since more mass abosrb more heat