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3 years ago

What is Q= mc delta t

Chemistry

1 answer:

Mariulka [41]3 years ago

6 0

Answer:

Explanation:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

The substances with higher value of specific heat capacity require more heat to raise the temperature by one degree as compared the substances having low value of specific heat capacity.For example,

The specific heat capacity of oil is 1.57 j/g. K and for water is 4.18 j/g.K. So, water take a time to increase its temperature by one degree by absorbing more heat while oil will heat up faster by absorbing less amount of heat.

Consider that both oil and water have same mass of 5g and change in temperature is 15 K. Thus amount of heat thy absorbed to raise the temperature is,

For oil:

Q = m.c. ΔT

Q = 5 g× 1.67 j/g K × 15 K

Q = 125.25 j

For water:

Q = m.c. ΔT

Q = 5 g× 4.18 j/g K × 15 K

Q = 313.5 j

we can observe that water require more heat which is 313.5 j to increase its temperature.

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Answer : The $\Delta G$ for this reaction is, -88780 J/mole.

Solution :

The balanced cell reaction will be,

$Cu(s)+2Ag^+(aq)\rightarrow Cu^{2+}(aq)+2Ag(s)$

Here, magnesium (Cu) undergoes oxidation by loss of electrons, thus act as anode. silver (Ag) undergoes reduction by gain of electrons and thus act as cathode.

The half oxidation-reduction reaction will be :

Oxidation : $Cu\rightarrow Cu^{2+}+2e^-$

Reduction : $2Ag^++2e^-\rightarrow 2Ag$

Now we have to calculate the Gibbs free energy.

Formula used :

$\Delta G^o=-nFE^o$

where,

$\Delta G^o$ = Gibbs free energy = ?

n = number of electrons to balance the reaction = 2

F = Faraday constant = 96500 C/mole

$E^o$ = standard e.m.f of cell = 0.46 V

Now put all the given values in this formula, we get the Gibbs free energy.

$\Delta G^o=-(2\times 96500\times 0.46)=-88780J/mole$

Therefore, the $\Delta G$ for this reaction is, -88780 J/mole.

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3 years ago

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3 years ago

Increased use of incineration is sometimes advocated as a safe way to dispose of chemical waste. But opponents of incineration p

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Answer:

Option A is correct.

At the two incinerators at which leaks were reported, staff had had only cursory training on the proper procedures for incinerating chemical waste.

Explanation:

The main aim of the argument presented is to talk down the use of burning by incinerators method to dispose chemical waste. The argument presents great points in that there were 40 incidents at two existing commissioned incinerators in the last year where unexpected releases of dangerous chemical agents happened.

So, basically, the argument is all about how the high frequency of the unsuspected release of dangerous chemical agents should discourage this method of chemical waste disposal.

The argument then concluded that if more chemical waste are disposed using the burning by incinerator method, there will be more unsuspected release of dangerous chemicals.

We are then required to find the statement that most weakens the conclusion that there will be more toxic releases if more chemical waste are burned.

Analysing the Statements one by one

Statement A

This statement provides a possible reason for this high frequency of dangerous chemical releases. It states that the staff haven't been properly trained. So, this means that properly training the staff should most likely lead to lesser cases of toxic releases into the environment.

This is the statement that most weakens the conclusion.

Statement B

The conclusion wasn't about the incinerator method being the safest method. It was about whether increased incineration would lead to more toxic relaeses. So, this doesn't affect the conclusion.

Statement C

This statement says that incineration can be increased without building new incinerators by tapping into unused capacity at the old incinerators. Also doesn't affect rhe conclusion whether increased use of incineration will lead to more toxic leaks.

Statement D

This statement strengthens the argument; which is the opposite of what we're aiming to achieve.

Statement E

This statement hints that the toxic leaks do not have that much of a harmful effect because the toxic releases do not go beyond the property of the incinerator. This also doesnt tackle the conclusion about the frequency of leaks, it only addresses how not harmful the toxic leaks can be.

Hope this Helps!!!

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3 years ago