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vovangra
1 month ago
9

in sample of elemental bromine, 55% or the atoms are Br-79, and the remainder are Br-81. if this sample is typical of naturally

occurring bromine, what is the average atomic mass of bromine?
Chemistry
1 answer:
KiRa [2.9K]1 month ago
3 0

Answer:

The typical atomic weight of bromine is 79.9 amu.

Explanation:

Provided information:

Br⁷⁹ constitutes 55% of the sample

Br⁸¹ constitutes 45% of the sample

What is the average atomic weight of bromine?

Calculation formula:

Average atomic mass = [isotope mass × its proportion] + [isotope mass × its proportion] +...[ ] / 100

We can now insert the known values into the formula.

Average atomic mass = [55 × 79] + [81 × 45] / 100

Average atomic mass = 4345 + 3645 / 100

Average atomic mass = 7990 / 100

Average atomic mass = 79.9 amu

The typical atomic weight of bromine is 79.9 amu.

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lions [2927]

Answer:

The enthalpy of the second intermediate equation is altered by halving its value and changing the sign.

Explanation:

Let's examine both the first and second intermediate reactions alongside the overall equation concerning the examined process;

First reaction;

Ca (s) + CO₂ (g) + ½O₂ (g) → CaCO₃ (s) ΔH₁ = -812.8 kJ

Second reaction;

2Ca (s) + O₂ (g) → 2CaO (s) ΔH₂ = -1269 kJ

Thus, the overall reaction becomes;

CaO (s) + CO₂ (g) → CaCO₃ (s) ΔH =?

According to Hess's law, which states that the total heat change in a reaction is equal to the sum of the heat changes for each step, we cannot simply sum the enthalpies for this overall reaction. Instead, we obtain the overall enthalpy by halving the second intermediate reaction's enthalpy and changing its sign before adding, as illustrated below;

Enthalpy of Intermediate reaction 1 + ½(-Enthalpy of Intermediate reaction 2) = Enthalpy of Overall reaction

7 0
1 month ago
How many grams of alcl3 are required to make a 2.25m solution in 30.0 g of water?
Alekssandra [3086]
The formula for molality is \frac{\text{weight of solute (g)}}{\text{molecular weight X Weight of solvent (Kg)}}

Given: A solution's molality equals 2.25 m
The weight of the solvent is 30 g, which is the same as 0.030 kg
Molecular weight of AlCl3 is 133.34 g/mol

Thus, we have the equation, 2.25 = \frac{\text{weight of solute (g)}}{\text{133.34 X 0.030}}
Therefore, the weight of the solute (g) becomes 9.00 g

Hence, <span>9.00 g of AlCl3 is necessary for creating a 2.25m solution in 30.0 g of water</span>
8 0
14 days ago
Pyridine rings can also under electrophilic aromatic substitution. given 2-methoxypyridine below, draw the expected major produc
alisha [2963]
Co2 is indeed the correct answer, my friend.
8 0
23 days ago
A student is given a 2.002 g sample of unknown acid and is told that it might be butanoic acid, a monoprotic acid (HC4H7O2, equa
KiRa [2933]
The unknown acid is identified as either butanoic acid or ascorbic acid. To ascertain the number of moles based on the given molarity, we utilize the following relationship: Molarity of NaOH solution = 0.570 M and Volume of solution = 39.55 mL. Utilizing the values in the provided equation, we derive the necessary data. The equation governing NaOH and monoprotic acid reactions indicates that one mole of NaOH reacts with one mole of HX, resulting in 0.0225 moles of the monoprotic acid. Conversely, in the case of NaOH and diprotic acid interactions, the stoichiometry is such that two moles of NaOH engage with one mole of diprotic acid. Consequently, we can calculate moles for butanoic acid with a mass of 2.002 g and a molar mass of 88 g/mol, leading us to the conclusion that both butanoic and ascorbic acids represent the unknown acid being neutralized.
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21 day ago
Which equation represents a spontaneous reaction?
Anarel [2989]

Answer:

D) Mn + Ni2+ ⇒ Mn2+ + Ni

Explanation:

A spontaneous process can occur in a specific direction without requiring any energy input from external sources. Such reactions happen naturally. In these spontaneous processes, the entropy change is positive (ΔS), the enthalpy change is negative (ΔH), and most importantly, ΔG (the change in free energy) is negative.

To identify which reaction is spontaneous, we analyze the electrode potentials of the involved species. The species with a more negative reduction potential can displace the other from its aqueous solution. In this case, since the reduction potential for Mn^2+ is -1.19 V compared to nickel's -0.25 V, manganese will thus naturally displace Ni^2+ from solution as indicated in the solution above.

5 0
25 days ago
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