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3 years ago

Help please all please

Chemistry

2 answers:

Luden [163]3 years ago

5 0

Answer:

I don’t want to download a pdf that I don’t know what it is…

Also, brainly strictly says that we can’t post questions about a test or quiz that is found in school…

Explanation:

Lilit [14]3 years ago

3 0

Answer:

wnich subject and which class pdf i will help you tell me

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Metallic bonding is...

kap26 [50]

Answer:

d an attraction between positive ions and electrons

7 0

2 years ago

When N2(g) reacts with H2(g) to form NH3(g), 92.2 kJ of energy are evolved for each mole of N2(g) that reacts. Write a balanced

Naddika [18.5K]

Answer:

N₂ + 3H₂ → 2NH₃ ΔH = - 92.2KJ

Explanation:

Let's write out the chemical equation between Nitrogen and Hydrogen to Form Ammonia.

Nitrogen + Hydrogen = Ammonia

N₂ + H₂ → NH₃

A Thermochemical Equation is a balanced stoichiometric chemical equation that includes the enthalpy change, ΔH.

The balanced stoichiometric chemical equation is given as;

N₂ + 3H₂ → 2NH₃

92.2 kJ of energy are evolved for each mole of N2(g) that reacts. And from the equation, 1 mole of N2 reacts.

The enthalpy change, ΔH = - 92.2KJ. The negative sign is because heat is being evolved.

The balanced thermochemical equation;

N₂ + 3H₂ → 2NH₃ ΔH = - 92.2KJ

6 0

3 years ago

The half life of radon-222 is 3.8 days. How Much of a 100g sample is left after 15.2 days

professor190 [17]

Answer:

6.2 g

Explanation:

In a first-order decay, the formula for the amount remaining after n half-lives is

$N = \frac{N_{0}}{2^{n}}$

where

N₀ and N are the initial and final amounts of the substance

1. Calculate the number of half-lives.

If $t_{\frac{1}{2}} = \text{3.8 da}$

$n = \frac{t}{t_{\frac{1}{2}}} = \frac{\text{15.2 da}}{\text{3.8 da}}= \text{4.0}$

2. Calculate the final mass of the substance.

$\text{N} = \frac{\text{100 g}}{2^{4.0}} = \frac{\text{100 g}}{16} = \text{6.2 g}$

4 0

3 years ago

A certain process has ΔH° > 0, ΔS° < 0, and ΔG° > 0. The values of ΔH° and ΔS° do not depend on the temperature. Which

tino4ka555 [31]

Answer: It is non-spontaneous at all T.

Explanation:

According to Gibb's equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G$ = Gibbs free energy = +ve

$\Delta H$ = enthalpy change = +ve

$\Delta S$ = entropy change = -ve

T = temperature in Kelvin

$\Delta G$ = +ve, reaction is non spontaneous

$\Delta G$ = -ve, reaction is spontaneous

$\Delta G$ = 0, reaction is in equilibrium

Putting in the values:

$\Delta G=(+ve)-T(-ve)$

$\Delta G=(+ve)(+ve)=+ve$

Reaction is non spontaneous at all temperatures.

4 0

3 years ago

The half life for the decay of carbon-14 is 5.73 x 10 years. Suppose the activity due to the radioactive decay of the carbon-14

Elena-2011 [213]

Answer:

Age of the atifact is $4.2\times 10^{2}$ years

Explanation:

For first -order radioactive decay- $A_{t}=A_{0}(\frac{1}{2})^{\frac{t}{t_{\frac{1}{2}}}}$
$A_{t}$ represents activity of radioactive nuclide after t time, $A_{0}$ represents initial activity of radioactive nuclide and $t_{\frac{1}{2}}$ represents half-life
Here, $A_{t}=19Bq$ , $A_{0}=20Bq$ and $t_{\frac{1}{2}}=5.73\times 10^{3}years$