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GREYUIT [131]
2 years ago
14

The first electron shell of an atom is complete when it has ___ electrons and the second electron shell is complete when it has

___ electrons and the third electron shell is complete when it has ___ electrons The fir Group of answer choices 2, 4 ,6 4, 8, 20 2, 6, 18 8, 2, 32 2, 8, 18
Chemistry
1 answer:
elena-s [515]2 years ago
5 0

Answer:

2, 8, 8

Explanation:

The first electron shell always has 2 electrons when it is complete. The second electron shell and 3rd shell can hold 8 when completed.

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28) Consider a 21.0 mL sample of pure lemon juice with a citric acid (H3C6H5O7) concentration of 0.30M. a. How many moles of cir
Damm [24]
<h3>#a. Answer:</h3>

0.0063 mole

<h3>Solution and explanation:</h3>

We are given 21.0 mL citric acid with a concentration of 0.30 M

Part a requires we calculate the number of moles of citric acid.

We need to know how to calculate the concentration of a solution;

Concentration or molarity = Number of moles ÷ Volume of the solution

Thus;

Number of moles = Concentration × Volume

Hence;

Moles = 0.30 M × 0.021 L

         = 0.0063 mole

<h3>#b. Answer</h3>

1.21 g citric acid

<h3>Solution</h3>

Part B

We are required to calculate the mass of citric acid in the sample

Number of moles of a compound is calculated by dividing its mass by its molar mass.

Molar mass of Citric acid = 192.124 g/mol

Moles of citric acid = 0.0063 mole

But; Mass = Number of moles × Molar mass

Mass of citric acid = 0.0063 mol × 192.124 g/mol

                             = 1.21 g citric acid

<h3>#c. Answer</h3>

4.167 mL

<h3>Solution:</h3>

Part C

We are required to determine the initial volume before dilution;

We have;

Initial concentration (M1) = 0.30 M

Final volume (V2) = 250 mL or 0.25 L

Final concentration (M2) = 0.0050 M

Using the dilution formula we can get the initial volume;

Therefore, since; M1V1 =M2V2

V1 = M2V2÷M1

   = (0.0050 × 0.25)÷ 0.30

   = 0.004167 L or

   = 4.167 mL

Therefore, the initial volume of the solution is 4.167 mL

8 0
3 years ago
Convert 146 calories to kilojoules need to know ASAP
Vikentia [17]
610.864 Energy result in kilojoules:
5 0
2 years ago
Compare the polymerisation reaction used to produce poly(ethene) with the
butalik [34]

Answer:

See explanation

Explanation:

Polymerization is the process whereby two or more monomers link together to form a compound of high molecular mass called a polymer.

There are two kinds of polymers;

-Addition polymers

-Condensation polymers

Addition polymers are formed by the joining of two or more monomers  to form a polymer without the elimination of a small molecule.

Condensation polymers are formed by the joining of two or more molecules  to form polymers with the elimination of a small molecule.

The main difference between polyethene and polyester is that polyethene is an addition polymer while polyester is a condensation polymer.

In polyethene, ethene molecules are joined together having the repeating unit as [-CH2-CH2-]n.

In polyester, the polymer arises from the reaction of carboxylic acid and an alcohol and loss of water molecules.

5 0
2 years ago
What is percent composition of carbon in c2h6o3
zubka84 [21]

the percentage composition of carbon is 30.77%

5 0
3 years ago
Cd(s)+2HCI(aq)---- H2(g)+CdCl2(aq). what volume in liters of 0.81m HCI solution would be needed to fully react with 32.71g Cd. a
BigorU [14]

Answer:

0.718L of 0.81M HCl are required

Explanation:

Based on the reaction:

Cd(s)+2HCI(aq) → H2(g)+CdCl2(aq)

<em>1 mol of Cd reacts with 2 moles of HCl</em>

<em />

To solve this question we must, as first, find the moles of Cd. With the moles of Cd we can find the moles of HCl needed to react completely with the Cd. With the moles and the molarity we can find the volume:

<em>Moles Cd -Molar mass: 112.411g/mol-:</em>

32.71g * (1mol / 112.411g) = 0.2910 moles Cd

<em>Moles HCl:</em>

0.2910 moles Cd * (2 moles HCl / 1mol Cd) =

0.5820 moles HCl

<em>Volume:</em>

0.5820 moles HCl * (1L / 0.81moles) =

<h3>0.718L of 0.81M HCl are required</h3>
6 0
2 years ago
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