Can something be both a mixture and a pure substance? Explain using examples.

grigory [225]

I believe they’re both true.

5 0

3 years ago

A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25 ?C. The initial concentrations of Pb2+ and Cu2+ are

VARVARA [1.3K]

Answer:

a) Ecell = 0.5123 V

b) Ecell = 0.4695 V

c) [Pb2 +] = 4.75 M

Explanation:

a)

The reaction at the cathode is represented as follows:

Cu2 + + 2e- -> Cu (s) Eocathode = 0.34 V

The reaction at the anode is equal to:

Pb (s) -> Pb2 + + 2e- Eoanode = -0.13 V

The number of moles of the electrons that are involved is equal to n = 2

Standard cell potential equals Eo = Eocathode - Eoanode = 0.34 V- (-0.13 V) = 0.47 V

The initial cell potential can be calculated with the following formula:

Ecell = Eocell - - 0.0592 / n) log ([(Pb2 +)] / [(Cu2 +)]) = 0.47 - (0.0592 / 2) log (0.052 / 1.4) = 0.5123 V

b)

The reaction in the cell is equal to:

Cu2 + + Pb (s) -> Cu (s) + Pb2 +

The concentration of Cu2 that gives the exercise is equal 0.2 M

Therefore, the change in concentration for Cu2 + is equal to:

Cu2 + = 1.4 M - 0.2 M = 1.2 M

We use the formula from part a)

Ecell = Eocell - (0.0592 / n) log ([(Pb2 +)] / [(Cu2 +)]) = 0.47 - (0.0592 / 2) log (1,252 / 1.2) = 0.4695 V

c)

To find the concentration of Pb2 + when there is a potential change in the cell of 0.37 V, we must clear the concentration of Pb2 + from the following formula:

Eccell = Echocell - (0.0592 / n) log (([Pb2 +]) / ([Cu2 +]))

0.0296 log ([Pb2 +] / [Cu2 +]) = (Eocélula - Ecélula / 0.0296)

Clearing Pb2 +:

[Pb2 +] = 4.75 M

8 0

3 years ago

Calculate the amount of heat needed to melt 99.9 g of solid acetic acid (HCH,CO2) and bring it to a temperature of 85.1 °C. Roun

Nadusha1986 [10]

Q = 1.161 J/kg of heat is required to melt 99.9 g of solid acetic acid (HCH,CO2). Q = mL(Latent heat is the energy emitted or absorbed by a body while changing it state ). (Latent heat is the energy released or absorbed by a body while changing it state ).

Apply the equation Q = mL where:

Energy is Q. (J)

m = Mass (g)

L = Acetic acid's latent heat of fusion 192(J/g) = J/g

Q is equal to 0.099 kg times 11.73 kj/mol.

Q = 1.161J/kg.

<h3>What is latent heat, and what varieties are there?</h3>

Latent heat is the amount of energy that a substance experiencing a change in state, such as ice turning into water or water turning into steam, can absorb or release while maintaining a constant temperature and pressure. Types: The material exists in three states: solid, liquid, and gaseous.

<h3>What does "sensible heat" mean?</h3>

Heat that can actually be felt is considered to be sensible heat. Instead of the phase shifting, energy is what causes the temperature to vary as it moves from one system to another. For instance, it warms the water instead of melting the ice.

Learn more about specific heat on:

brainly.com/question/11297584

#SPJ4

3 0

2 years ago

An analytical chemist weighs out 0.188 g of an unknown triprotic acid into a 250 mL volumetric flask and dilutes to the mark wit

Anon25 [30]

<u>Answer:</u> The molar mass of unknown triprotic acid is 97.66 g/mol

<u>Explanation:</u>

To calculate the molarity of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$