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ivanzaharov [21]
3 years ago
14

Can y’all help with question 17

Chemistry
1 answer:
GalinKa [24]3 years ago
5 0

Answer:

7. Option 2. Atom 1 and Atom 4

8. The same number of valence electron

Explanation:

7. Determination of which symbol represent an isotope.

Isotopes are atoms having the same atomic number but different mass number due to the difference in the neutron number.

From the question given above, the following were obtained:

Z => atomic number

A => mass number

Atom >>> Isotope >>>>> Z >>>> A

1 >>>>>>> ¹⁷₇E >>>>>>>> 7 >>>> 17

2 >>>>>>> ¹⁷₈E >>>>>>> 8 >>>> 17

3 >>>>>>> ¹⁸₆E >>>>>>> 6 >>>> 18

4 >>>>>>> ¹⁸₇E >>>>>>> 7 >>>> 18

From the table above, only atom 1 and 4 has the same atomic number. Hence, atom 1 and atom 4 are isotopes.

8. To know the correct answer to the question, we shall write the electronic configuration of magnesium and calcium. This can be obtained as follow:

Mg (12) => 1s² 2s²2p⁶ 3s²

Valence electron => 2

Ca (20) => 1s² 2s²2p⁶ 3s²3p⁶ 4s²

Valence electron => 2

We can see that magnesium and calcium both have the same valence electron. Hence, they will have similar chemical properties.

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What volume of a concentrated HCl solution, which is 36.0% HCl by mass and has a density of 1.179 g/mL, should be used to make 5
charle [14.2K]

Answer:

The volume we need is 8.89 mL

Explanation:

We analyse data:

36 % by mass → 36 g of HCl in 100 g of solution

Solution's density = 1.179 g/mL

5.20L → Volume of diluted density

pH = 1.70 → [H⁺] = 10⁻¹'⁷⁰ = 0.0199 M

 HCl    →       H⁺     +    Cl⁻

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pH can gives the information of protons concentrations, so as ratio is 1:1, 0.0199 M is also the molar concentration of HCl

Let's verify the molar concentration of the concentrated solution:

We convert the mass to moles: 36 g / 36.45 g/mol = 0.987 moles

As the solution mass is 100 g, we apply density to find out the volume:

Density = Mass / volume → Volume = Mass / Density

Volume = 100 g / 1.179 g/mL → 84.8 mL

Let's convert the volume from mL to L in order to define molarity

84.8 mL . 1L/ 1000mL = 0.0848 L

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Let's apply the dilution formula:

M concentrated . V concentrated = M diluted . V diluted

11.6 M . V concentrated = 0.0199M . 5.20L

V concentrated = (0.0199M . 5.20L) / 11.6M → 8.89×10⁻³L

We can say, that the volume we need is 8.89 mL

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