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3 years ago

6

I need your help please with this question!!

1 answer:

castortr0y [4]3 years ago

6 0

Hey there!

The first one:

The 20 means it has 20 protons. The 42 means the sum of protons and neutrons is 42, so that means 20 protons plus 22 neutrons is 42 total. There is no charge noted, so the number of electrons is equal to the number of protons.

This atom has 20 protons, 22 neutrons, and 20 electrons.

The second one:

The 20 means it has 20 protons. The 44 means the sum of protons and neutrons is 44, so that means 20 protons plus 24 neutrons is 44 total. There is no charge noted, so the number of electrons is equal to the number of protons.

This atom has 20 protons, 24 neutrons, and 20 electrons.

Hope this helps!

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A chemist places 2.5316 g of Na 2SO 4 in a 100 mL volumetric flask and adds water to the mark. She then pipets 15 mL of the resu

Lera25 [3.4K]

Answer:

The concentration of the most dilute solution is 0.016M.

Explanation:

First, a solution is prepared and then it undergoes two subsequent dilutions. Let us calculate initial concentration:

$[Na_{2}SO_{4}]=\frac{moles(Na_{2}SO_{4})}{liters(solution)} =\frac{mass((Na_{2}SO_{4}))}{molarmass(moles(Na_{2}SO_{4}) \times 0.100L)} =\frac{2.5316g}{142g/mol\times 0.100L } =0.178M$

<u>First dilution</u>

We can use the dilution rule:

C₁ x V₁ = C₂ x V₂

where

Ci are the concentrations

Vi are the volumes

1 and 2 refer to initial and final state, respectively.

In the first dilution,

C₁ = 0.178 M

V₁ = 15 mL

C₂ = unknown

V₂ = 50 mL

Then,

$C_{2}=\frac{C_{1} \times V_{1} }{V_{2}} =\frac{0.178M \times 15mL}{50mL} =0.053M$

<u>Second dilution</u>

C₁ = 0.053 M

V₁ = 15 mL

C₂ = unknown

V₂ = 50 mL

Then,

$C_{2}=\frac{C_{1} \times V_{1} }{V_{2}} =\frac{0.053M \times 15mL}{50mL} =0.016M$

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4 years ago

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Mass of $CO_2$ = $44\times 0.3167=13.93\ \text{g}$

The mass of carbon dioxide formed simultaneously is $13.93\ \text{g}$ .

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