All categories

3 years ago

The mass of half mole of electrons is about (mass of electron= 9.1 * 10^-28g)

1 answer:

7 0

One electron has a mass of 9.10938291 x 10^−31 kg. One mole of electrons contains 6.022x10^23 electrons where half of a mole is has 3.011x10^23 electrons. Therefore, the mass of half a mole of electrons would be 2.74x10^-7. Hope this answers the question. Have a nice day.

You might be interested in

What motion causes thermal energy?

OLga [1]

Thermal energy causes of motion of

1. mixing water molecules contained in a beaker.

2.molecules in soild liquid and gas phases

3. mixing molecules together

4. molecules that have reached equilibrium

7 0

3 years ago

What would be the greatest difference in using an open ceramic coffee mug rather than an insulated mug with a lid as a calorimet

adoni [48]

The answer is number 4 or the exchange of energy with the surroundings. Calorimetry is a measurement of energy that is formed or absorbed in a certain process. The calorimeter is the instrument used in order to measure the energy. It is recommended that a calorimeter should be a closed system so as to measure precisely the energy and avoid or lessen the exchange of energy with the surroundings. Thus, comparing an open ceramic mug and an insulated mug with a lid, the greatest difference is the energy lost to the surroundings.

4 0

3 years ago

Read 2 more answers

An iron bar at 200c is placed in thermal contact with an identical iron bar at 120c in an isolated system

Step2247 [10]

Conduction: In the conduction, the heat is transferred from the hotter body to the colder body until the temperature on both bodies are equal.

In thermal equilibrium, there is no heat transfer as the heat is transferred till the temperature on the bodies are not same.

In the given problem, an iron bar at 200°C is placed in thermal contact with an identical iron bar at 120°C in an isolated system. After 30 minutes, the thermal equilibrium is attained. Then, the temperature on both iron bars are equal.Both iron bars are at 160°C in an isolated system.

But in an open system, the temperatures of the iron bars after 30 minutes would be less than 160°C. There will be heat lost to the surrounding. The room temperature is 25°C. There will be exchange of the heat occur between the iron bars and the surrounding. But It would take more than 30 minutes for both iron bars to reach 160°C because heat would be transferred less efficiently.

7 0

3 years ago

Read 2 more answers

H2, N2, O2 molecules. . . A)must be polar. must be nonpolar. . B)can be polar or nonpolar depending on geometric . C)configurati

LenKa [72]

Answer: The correct option is A.

Explanation: The given molecules are the molecules of same element.

These molecules are considered as diatomic species.

Polar molecules are the molecules in which some polarity is present in the bond. These molecules are formed when there is some difference in the electronegativities of the elements. Example: HCl

Non-polar molecules are the molecules where no polarity is present in the bond. These molecules are formed when there is no difference in the electronegativities of the elements. Example: $H_2, O_2$

The given molecules are non-polar in nature.

Hence, these molecules must be non-polar. So, the correct option is A.

6 0

3 years ago

Read 2 more answers

When 3.93 grams of lactic acid, CHoOs(s), are burned in a bomb

aliya0001 [1]

The heat released in the combustion of lactic acid is absorbed by the

calorimeter and in the decomposition of the lactic acid.

ΔH°f of lactic acid is approximately -716.2 kJ

Reasons:

Known parameters are;

Mass of the lactic acid = 3.93 grams

Heat capacity of the bomb calorimeter = 10.80 kJ·K⁻¹

Change in temperature of the calorimeter, ΔT = 5.34 K

ΔHrxn = ΔErxn

ΔH°f of H₂O(l) = -285.8 kJ·mol⁻¹

ΔH°f of CO₂(g) = -393.5 kJ·mol⁻¹

The chemical equation for the reaction is presented as follows;

C₃H₆O₃ + 2O₂ → 3CO₂ + 3H₂O

The heat of the reaction = 10.80 kJ·K⁻¹ × 5.34 K = 57.672 kJ

Molar mass of C₃H₆O₃ = 90.07 g/mol

Number of moles of C₃H₆O₃ = $\dfrac{3.93 \, g}{90.07 \, g/mol}$ = 0.043633 moles

Number of moles of CO₂ produced = 3 × 0.043633 moles = 0.130899 moles

Heat produced = 0.130899 mole × -285.8 kJ·mol⁻¹ = -37.4109342 kJ

Moles of H₂O produced = 0.130899 moles

Heat produced = 0.130899 mole × -393.5 ≈ -51.51 kJ

Therefore, we have;

Heat absorbed by the lactic acid = ΔH°f of H₂O + ΔH°f of CO₂ + Heat absorbed by the calorimeter

Which gives;

Heat absorbed by lactic acid = -37.4109342 kJ - 51.51 kJ + 57.672 kJ ≈ -31.249 kJ

The heat absorbed by the lactic acid ≈ -31.249 kJ

$\Delta H^{\circ}f \ of \ C_3H_6O_3 = \dfrac{-31.249}{0.043633} \approx -716.2$

ΔH°f of C₃H₆O₃ ≈ -716.2 kJ

Heat of formation of lactic acid ≈ -716.2 kJ.

Learn more here:

brainly.com/question/13185938

5 0

2 years ago