Chemistry, 05.02.2020 12:04 makylahoyle

Acold piece of aluminum and a hot piece of copper have the same masses. the specific heat capacity of alumin?
a cold piece of aluminum and a hot piece of copper have the same masses. the specific heat capacity of aluminum is more than double that of copper. if the aluminum and the copper are put in thermal contact, which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium? assume an isolated system consisting of only the two pieces of metals. ok, this is confusing.. i thought heat lost and heat gained are always equal to each other? ?

Answers: 3

Show answers

Answers

Answer from: bloom826

Yes, heat lost and heat gained are equal to each other, but the temperature that the change in temperature are different.

Look, heat exchange = m*C*temperature change.
Where m is mass and C is specific heat.

If m are the same

You can write

heat gained by metal 1 = C of metal 1 * temperature increase

heat lost by metal 2 = C of metal 2 * temperature decrease

So, C of metal 1 * temperature increase = C of metal 2 * temperature decrease.

Then the metal with the lower C will experience a bigger change of temperature.

Please, let me know if this helped you.

Answer from: Quest

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh $pcl_{3}$ +δh $cl_{2}$ ] - [δh $pcl_{5}$ ]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

Answer from: Quest

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is $1s^{2}2s^{2}2p^{6}3s^{1}$ and electronic configuration of phosphorous is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$ .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

$3na + p \rightarrow na_{3}p$

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.