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gladu [14]
2 years 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:
Gwar [14]2 years ago
3 0

Answer:

The average atomic mass of bromine is 79.9 amu.

Explanation:

Given data:

Percentage of Br⁷⁹ = 55%

Percentage of Br⁸¹ = 45%

Average atomic mass of bromine = ?

Formula:

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

Now we will put the values in 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 average atomic mass of bromine is 79.9 amu.

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Convert 2.1 mole of Al2(SO4)3 ionic units to a number of particles.​
Semenov [28]

1.26 x 10²⁴particles

Explanation:

Given parameters:

Number of moles of the compound = 2.1 moles

Unknown:

Number of particles contained in the compound = ?

Solution:

A mole can be defined as the amount of a substance that contains Avogadro's number of particles 6.02 x 10²³.

The particles mentioned here can be atoms, molecules, formula units, ions, electrons, protons, neutrons and so forth.

To solve for the number of moles:

   Number of particles  = number of moles x 6.02 x 10²³

Number of particles = 2.1 x  6.02 x 10²³ = 12.64 x  10²³ = 1.26 x 10²⁴particles

Learn more:

mole calculation brainly.com/question/1841136

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8 0
2 years ago
A rigid, 28-L steam cooker is arranged with a pressure relief valve set to release vapor and maintain the pressure once the pres
MaRussiya [10]

Answer:

\Delta S_{source}>-1.204\frac{kJ}{K}

Explanation:

Hello!

In this case, given the initial conditions, we first use the 10-% quality to compute the initial entropy:

s_1=s_{f,175kPa}+q*s_{fg,175kPa}\\\\s_1=1.4850\frac{kJ}{kg*K} +0.1*5.6865\frac{kJ}{kg*K}=2.0537\frac{kJ}{kg*K}

Now the entropy at the final state given the new 40-% quality:

s_2=s_{f,150kPa}+q*s_{fg,150kPa}\\\\s_2=1.4337\frac{kJ}{kg*K} +0.4*5.7894\frac{kJ}{kg*K}=3.7495\frac{kJ}{kg*K}

Next step is to compute the mass of steam given the specific volume of steam at 175 kPa and the 10% quality:

m_1=\frac{0.028m^3}{(0.001057+0.1*1.002643)\frac{m^3}{kg} } =0.274kg\\\\m_2=\frac{0.028m^3}{(0.001053+0.4*1.158347)\frac{m^3}{kg} } =0.0603kg

Then, we can write the entropy balance:

\Delta S_{source}+\frac{Q}{T_1} -\frac{Q}{T_2} +s_2m_2-s_1m_1-s_{fg}(m_2-m_1)>0

Whereas sfg stands for the entropy of the leaving steam to hold the pressure at 150 kPa and must be greater than 0; thus we plug in:

Which is such minimum entropy change of the heat-supplying source.

Best regards!

3 0
2 years ago
Magnesium reacts with a certain element to form a compound with the general formula MgX. What would the most likely formula be f
Rama09 [41]

Answer:

K2X

Explanation:

Valency can be defined as the combining power of an element. It is the valency that dictates the value an element will have when writing a chemical formula for its compound.

MgX is a compound of magnesium and an element X. The valency of magnesium in most of its compound is +2. Now for the 2 to have been absent in the chemical formula, this shows that the element X itself have a valency if -2 for the valencies of both to have canceled out.

Now considering the element potassium, it is an alkaline metal belonging to group 1 of the periodic table. Hence, it is expected that it has a valency of +1

Forming a compound with element X means there would be an exchange of valencies between the two. We have established that x has a valency of -2. The formula of the compound thus formed by exchanging the valencies of both element would be K2X

4 0
2 years ago
A car moves at a speed of 50 kilometers/hour. Its kinetic energy is 400 joules. If the same car moves at a speed of 100 kilomete
lys-0071 [83]

ke prop to v^2


ke1/v1^2=ke2/v2^2


400/50x50=joules/100x100


400x2x2


1600j

8 0
2 years ago
We know from the relative amounts of 16O and 18O that global temperatures and global climate have changed over time. Why is it i
Andru [333]

Answer:

In order to take steps by humans for controlling the change in climate.

Explanation:

It is important that scientist find out the change which occurs in the climate with the passage of time by performing experiments and also repeat the experiments in order to verify their findings. Due to these experiments, scientists also find out the reasons behind of climate change which enable us to take steps in preventing the change that occurs in the environment. it is also important for scientists to be able to explain how they know that climate has changed over time in order to explain that he is not assuming or making predictions, he has to provide evidence for his statement which is only be possible through experiments.

3 0
2 years ago
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