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e-lub [12.9K]
4 years ago
5

How many electrons are in a neutral atom of bromine-81?

Chemistry
1 answer:
abruzzese [7]4 years ago
4 0

81 - 35 = 46
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What is a demonstration of the law of conservation of mass​
IrinaVladis [17]

Answer:

Explanation:

Law of Conservation of Mass: The law that states that matter cannot be created nor destroyed

Ex: Kelly ran across the room and bumped into her brother, pushing him to the floor. The kinetic energy she possessed because of her movement was transferred to her brother, causing him to move.

6 0
3 years ago
For many purposes we can treat methane as an ideal gas at temperatures above its boiling point of . Suppose the temperature of a
Elza [17]

Answer:

The volume decreases 5.5%

Explanation:

First, the question is incomplete, you are not giving the values of the temperatures and the pressure. However, I managed to find one similar question, and the given data is the temperature is lowered from 21 °C to -8°C, and the pressure decreased by 5%. If your data is different, you should only replace your data in the procedure, and you'll get an accurate result.

Now, with this data, let's see what we can do.

If this is an ideal gas, the equation to use is:

PV = nRT

Now, we know that this gas is suffering a decrease in temperature and pressure, but the moles stay the same so:

n₁ = n₂ = n

The constant R, is the same for both conditions. The only thing that differs here is the volume, temperature, and pressure. Therefore:

P₁V₁ = nRT₁   -----> n = P₁V₁ / RT₁

Doing the same with the pressure and volume 2 we have:

n = P₂V₂ / RT₂

Equalling both expressions and solving for V₂:

P₁V₁ / RT₁ = P₂V₂ / RT₂

V₂ = P₁T₂V₁ / P₂T₁

Now, as we know that P2 is 5% decreased from P1, so P2 = 0.95P1:

V₂ = P₁T₂V₁ / 0.95P₁T₁

The values of temperature in K:

T1 = 21+273 = 294 K

T2 = -8 + 273 = 265 K

Finally, let's calculate the volume:

V₂ = 264*P₁*V₁ / 294*0.95*P₁   ----> P cancels out  

V₂ = 264V₁ / 294*0.95

V₁ = 0.945V₂

With this, we can day that Volume 2 decreases.

Now the percentage change would be using the following expression:

%V = (V₁ - V₂ / V₁) * 100

Replacing the data we have:

%V = V1 - 0.945V₁ / V₁

%V = 0.055V₁ / V₁ * 100

%V = 5.5%

7 0
3 years ago
How many grams of cobalt (II) nitrate, Co(NO3)2, are required to make a 2.20%(w/v) aqueous solution in a 250 mL volumetric flask
shutvik [7]

Answer:

\large \boxed{\text{5.50 g}}

Explanation:

Percent means " per hundred," so % m/V means the grams of something in 100 mL of  volume.

\text{m/V \%} = \dfrac{\text{mass of solute} }{\text{volume of solution}} \times 100 \, \%

Data:

         m/V % = 2.20 %

V of solution = 250 mL

Calculations:

\text{2.20 \%} = \dfrac{\text{mass of solute} }{\text{250 mL}} \times 100 \, \%\\\\\text{Mass of solute} = \dfrac{2.20\, \% \times \text{250 mL}}{100 \%} = \text{5.50 g}\\\\\text{The mass of Co(NO$_{3}$)$_{2}$ is $\large \boxed{\textbf{5.50 g}}$}

8 0
3 years ago
What negative impact did chemistry have on society through the production and use of cfcs
ycow [4]
Hazardous coolants in refrigeration  units where replaced;) hope it helped have a good day!

5 0
3 years ago
During which phase of the moon do neap tides occur?
Setler79 [48]
Quarter moon is the correct answer
4 0
3 years ago
Read 2 more answers
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