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3 years ago

What would be the final temperature of a 73.174g sample

Chemistry

1 answer:

madreJ [45]3 years ago

3 0

The final temperature is -138 °C.

Explanation:

Using the equation of specific heat

$Q = m*c* del T$

We can easily find the final temperature of a 73.174 g of copper sample. As we know that specific heat is the amount of energy required to raise the temperature of the object to 1°C.

The specific heat of copper is known as 0.387 J/g°C and the initial temperature is said as 102 °C . The mass is given as 73.174 g. The heat released is 6800 J.

Since the heat is released the Q value will be negative.

$-6800=0.387*73.174*(T_{final}-102)$

$T_{final}-102=\frac{-6800}{0.387*73.174} =-240$

$T_{final} = -240+102=-138$

Thus, the final temperature is -138 °C.

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The free energy change for the following reaction at 25 °C, when [Cr3+] = 1.32×10-3 M and [Fe3+] = 1.14 M, is 131 kJ: Cr3+(1.32×

larisa [96]

Answer:

E°cell = - 1.3575 V

This reaction is spontaneous in the reverse direction

Explanation:

The given cell reaction:

Cr³⁺(1.32 × 10⁻³ M) + Fe²⁺(aq) → Cr²⁺(aq) + Fe³⁺(1.14 M)

The given Gibbs free energy: ΔG = 131 kJ = 131 × 10³ J (∵ 1 kJ = 10³ J)

As we know,

ΔG = - n F E°cell

Here, n - the number of moles of electrons transferred = 1

F - Faraday constant = 96500

E°cell - cell potential = ?

$\therefore E^{\circ }_{cell} = -\frac{\Delta G}{n \: F} = -\frac{131\times 10^{3}\, J}{1\, mol\times96500 \, C.mol^{-1}}$

$\Rightarrow E^{\circ }_{cell} = -1.3575\, V$

For a given chemical reaction if-

1. ΔG = negative and E°cell = positive

⇒ The reaction is spontaneous and proceeds spontaneously in the forward direction.

2. ΔG = positive and E°cell = negative

⇒ The reaction is non-spontaneous and proceeds spontaneously in the reverse direction.

Since, for this chemical reaction: 

Cr³⁺(1.32 × 10⁻³ M) + Fe²⁺(aq) → Cr²⁺(aq) + Fe³⁺(1.14 M)

ΔG = + 131 × 10³ J ⇒ positive

and, E°cell = - 1.3575 V ⇒ negative

Therefore, this reaction is spontaneous in the reverse direction.

6 0

3 years ago

What is the volume that you should dilute 30mL of a 12.0M H2SO4 solution to obtain a 0.160M H2SO4 solution?

shutvik [7]

To solve this problem, the dilution equation (M1 x V1 = M2 X V2) must be used. The given values in the problem are M1= 12.0 M, V1= 30 mL, and M2= 0.160 M. To solve for V2,
V2=M1xV1/M2
V2= (12x30)/0.16
V2= 2,250 mL.
The correct answer is 2.25 L.

8 0

2 years ago

Which binary molecular compound includes an element with five atoms of one element?

uranmaximum [27]

Answer:

For example, N2O4 is referred to as dinitrogen tetroxide, not dinitrogen tetraoxide, and CO is called carbon monoxide, not carbon monooxide.

...

Binary molecular (covalent) compounds.

Prefixes used in chemical nomenclature

prefix number of atoms

tetra- 4

penta- 5

hexa- 6

Explanation:

6 0

2 years ago

How long will it take for 100 grams of a substance with a half-life of 2 years to decay to a mass of 50 grams?

Elis [28]

Answer:

2 years to decay to a mass of 50g.

Explanation:

given:

100g of substance with a half life of 2 years

to a mass of 50g

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

ln 2 0.693

Half life T1/2 = ---------- = -----------

λ λ

where λ = rate constant

The initial amount of 100 grams is decaying to a mass of 50 grams is half of its initial value.

Therefore, it will take 2 years for the decay.

3 0

3 years ago

On 100 corex

Julli [10]

Answer:

P(total) = 164 mmHg

Explanation:

Given data:

Partial pressure of helium = 77 mmHg

Partial pressure of nitrogen = 87 mmHg

Total pressure of flask = ?

Solution:

According to Dalton law of partial pressure,

The total pressure inside container is equal to the sum of partial pressures of individual gases present in container.

Mathematical expression:

P(total) = P₁ + P₂ + P₃+ ............+Pₙ

Now we will solve this problem by using this law.

P(total) = P(He) + P(N₂)

P(total) = 77 mmHg + 87 mmHg

P(total) = 164 mmHg

3 0

2 years ago