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3 years ago

Describe the methods by which an electric potential develops in primary cells and dry cells.

Chemistry

2 answers:

nevsk [136]3 years ago

7 0

Answer:

In a primary cell, two electrodes (one of copper and other of zinc) of metal atoms are used. These electrodes are dipped in an electrolyte solution that causes the metals to produce their respective positive and negative ions.

In this way, the flow of charges takes place and supply the electricity to the source.

Unlike a primary cell, a dry cell contains paste of an electrolyte instead of the solution. The contents of electrolyte paste react with each other through a chemical process and convert the chemical energy into electrical energy.

Katarina [22]3 years ago

4 0

Answer:

In primary cells, an electric potential develops through chemical action between the plates within the cell. Positively charged ions of zinc enter the acid and free electrons released from zinc atoms collect on the zinc plate, which results in a negative charge. At the same time, positively charged ions of hydrogen from the acid remove free electrons from the copper plate, which becomes positively charged. Through a conducting material connecting the plates, free electrons move from the zinc plate to the copper plate as long as the chemical reaction lasts.

Dry cells also develop electric potential via chemical actions within the cell. Free electrons removed from the carbon rod collect on a zinc can. The rod exhibits a positive charge and the can becomes negatively charged; this allows for an electric potential to develop between these two items. Through a conducting material connecting the can to the rod, free electrons move from the can to the rod as long as the conducting path exists.

Explanation:

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How many moles are there in 100 grams of Na3PO4?

kondaur [170]

65.2 g x (1 mol/163.9 g) = 0.398 moles of Na3PO4.

5 0

3 years ago

How many grams of sodium acetate ( molar mass = 83.06 g/mol ) must be added to 1.00 Liter of a 0.200 M acetic acid solution to m

Pie

Answer: The mass of sodium acetate that must be added is 30.23 grams

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$

Molarity of acetic acid solution = 0.200 M

Volume of solution = 1 L

Putting values in above equation, we get:

$0.200M=\frac{\text{Moles of acetic acid}}{1L}\\\\\text{Moles of acetic acid}=(0.200mol/L\times 1L)=0.200mol$

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

$pH=pK_a+\log(\frac{[\text{salt}]}{[\text{acid}]})$

$pH=pK_a+\log(\frac{[CH_3COONa]}{[CH_3COOH]})$

We are given:

$pK_a$ = negative logarithm of acid dissociation constant of acetic acid = 4.74

$[CH_3COONa]=?mol$

$[CH_3COOH]=0.200mol$

pH = 5.00

Putting values in above equation, we get:

$5=4.74+\log(\frac{[CH_3COONa]}{0.200})$

$[CH_3COONa]=0.364mol$

To calculate the mass of sodium acetate for given number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Molar mass of sodium acetate = 83.06 g/mol

Moles of sodium acetate = 0.364 moles

Putting values in above equation, we get:

$0.364mol=\frac{\text{Mass of sodium acetate}}{83.06g/mol}\\\\\text{Mass of sodium acetate}=(0.364mol\times 83.06g/mol)=30.23g$

Hence, the mass of sodium acetate that must be added is 30.23 grams

7 0

3 years ago

What is the equilibrium constant of a reaction?

xeze [42]

Answer:

A. It is the ratio of the concentrations of products to the concentrations of reactants.

Explanation:

The equilibrium constant of a chemical reaction is the ratio of the concentration of products to the concentration of reactants.

This equilibrium constant can be expressed in many different formats.

For any system, the molar concentration of all the species on the right side are related to the molar concentrations of those on the left side by the equilibrium constant.
The equilibrium constant is a constant at a given temperature and it is temperature dependent.
The derivation of the equilibrium constant is based on the law of mass action.
It states that "the rate of a chemical reaction is proportional to the product of the concentration of the reacting substances. "

8 0

3 years ago

In a different experiment, the student uses a calorimeter which is perfectly insulated. She fills the calorimeter with 100.0 g o

alexdok [17]

Answer:

Explanation:

Mg + 2HCl = Mg Cl₂ + H₂

.594 g = .594 / 24.3

= .02444 mole

Heat evolved = msΔ T , m is mass of water ( solvant ) , s is specific heat of water , Δ T is rise in temperature

= 100 x 4.2 x ( 41.83 - 25 )

= 7068.6 J

.02444 mole of Mg evolves 7068.6 J of heat

1 mole of Mg evolves 7068.6 /.02444 J

= 289222.6 J

= 289 kJ .

Molar heat enthalpy = 289 kJ .

8 0

3 years ago

Which reactions are oxidation-reduction reactions? check all that apply. fes(s) 2hcl(aq) â†’ h2s(g) fecl2(g) agno3(aq) nacl(aq)

Dafna1 [17]

oxidation-reduction reactions are -

2C3H6(g) + 9O2(g) → 6CO2(g) + 6H2O(g)
Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

For reaction,

2C3H6(g) + 9O2(g) → 6CO2(g) + 6H2O(g)

On reactant side:

Oxidation state of Carbon = +2

Oxidation state of Oxygen = 0

On product side:

Oxidation state of Carbon = +4

Oxidation state of Oxygen = -2

Here, carbon's oxidation state is rising from +2 to +4. As a result, it is oxidizing and the oxygen's oxidation state is decreasing from 0 to -2. As a result, it is decreasing.

For reaction,

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

When reacting:

Iron's oxidation state is +3.

Carbon's oxidation state is +2.

On product side:

Iron's oxidation state is zero.

Carbon's oxidation state is +4.

Here, carbon's oxidation state is rising from +2 to +4. As a result, it is being oxidized and the iron's oxidation state is changing from +3 to 0. As a result, it is decreasing.

To learn more about oxidation-reduction from given link

brainly.com/question/5794822

#SPJ4

7 0

2 years ago