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denpristay [2]
2 years ago
7

The atomic number of nitrogen is 7. nitrogen-15 has a greater mass number than nitrogen-14 because the atomic nucleus of nitroge

n-15 contains _____. 8 neutrons 15 protons 7 neutrons 8 protons
Chemistry
2 answers:
schepotkina [342]2 years ago
7 0
8 neutrons (7 protons)
Paha777 [63]2 years ago
5 0

Answer: Option (a) is the correct answer.

Explanation:

Atomic number means the sum of total number of protons acquired by an atom.

So, when atomic number of nitrogen is 7 then it means there are 7 protons present.

Whereas atomic mass means the sum of total number of protons and neutrons present in an atom.

Therefore, nitrogen-15 is an isotope of nitrogen that will always have 7 protons when it is neutral in nature. Hence, in nitrogen-15 the number of protons and neutrons are calculated as follows.

                   Atomic mass = no. of protons + no. of neutrons

                             15 = 7 + no. of neutrons

                    no. of neutrons = 15 - 7

                                               = 8

Thus, we can conclude that the atomic nucleus of nitrogen-15 contains 8 neutrons.

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How many liters of 3.0 M NaOH solution will react with 2.4 mol H2SO4? (Remember to balance the equation.)
timurjin [86]

Answer:

1.6 L is the volume of NaOH that has reacted

Explanation:

The balanced reaction is:

H₂SO₄ + 2NaOH → Na₂SO₄  + 2H₂O

This is a neutralization reaction between a strong acid and a strong base. The products are the correspond salt and water.

We propose this rule of three:

1 mol of sulfuric acid needs 2 mol of NaOH to react to react

Then, 2.4 moles of H₂SO₄  will react with (2.4 . 2) / 1 = 4.8 moles of NaOH

As molarity is 3M, we can determine the volume of our solution

Molarity (M) = mol / volume(L) → Volume(L) = mol / Molarity

Volume(L) = 4.8 mol / 3 M = 1.6 L

3 0
2 years ago
For the Bradford assay, the instructor will make a Bradford reagent dye by mixing 50 ml of 95% v/v ethanol with 100 mg of Coomas
jolli1 [7]

Answer:

4,25% v/v H3PO4

Explanation:

The concentration of phosphoric acid (H3PO4) is expressed as a volume / volume percentage, which means:

%v/v H3PO4 = (mL of pure H3PO4/mL of solution)*100%

In other words, <u>we are only interested in the final volume of the solution to which the phosphoric acid was diluted, regardless of its composition</u>. Which in this case is 1 L (1000 mL).

We can then apply the following equation, commonly used to calculate the initial or final concentration (or volume) of a substance when it is diluted:

Ci*Vi=Cf*Vf

<u>Where</u>:

Ci, is the initial concentration of the substance.

Vi, the initial volume of the substance

Cf, the final concentration reached after dilution

Vf, the final volume of the solution at which the substance was diluted

In this case, the incognite would be the final concentration of H3PO4 reached after dilution, that is, Cf. Therefore, we proceed to clear Cf from the previous equation and replace our data:

Cf = (Ci*Vi)/Vf = (85% v/v * 50 mL)/1000 mL = 4,25 % v/v

Note that being up and down in the division, the mL unit is canceled to result in% v / v.

7 0
2 years ago
A solution is made by dissolving 58.125 g of sample of an unknown, nonelectrolyte compound in water. The mass of the solution is
e-lub [12.9K]

Answer:

molecular weight (Mb) = 0.42 g/mol

Explanation:

mass sample (solute) (wb) = 58.125 g

mass sln = 750.0 g = mass solute + mass solvent

∴ solute (b) unknown nonelectrolyte compound

∴ solvent (a): water

⇒ mb = mol solute/Kg solvent (nb/wa)

boiling point:

  • ΔT = K*mb = 100.220°C ≅ 373.22 K

∴ K water = 1.86 K.Kg/mol

⇒ Mb = ? (molecular weight) (wb/nb)

⇒ mb = ΔT / K

⇒ mb = (373.22 K) / (1.86 K.Kg/mol)

⇒ mb = 200.656 mol/Kg

∴ mass solvent = 750.0 g - 58.125 g = 691.875 g = 0.692 Kg

moles solute:

⇒ nb = (200.656 mol/Kg)*(0.692 Kg) = 138.83 mol solute

molecular weight:

⇒ Mb = (58.125 g)/(138.83 mol) = 0.42 g/mol

8 0
2 years ago
Fluorine gas is placed in contact with calcium metal at high temperatures to produce calcium fluoride powder. What is the formul
Mars2501 [29]

Answer:

Upper F subscript 2 (g) plus upper C a (s) right arrow with delta above upper C a upper F subscript 2 (s).

Explanation:

This is a chemical reaction problem.

In expressing any chemical reaction, we need to understand that there are reactants and products.

  • The reactants are the species on the left hand side that are combining.
  • The products are the species on the right hand side that are formed.
  • Every chemical reaction is obeys the law of conservation of matter i.e equal number of matter on both sides.

Using the statement of this problem, we can deduce that;

 Reactants are Fluorine gas and Calcium metal

  Product is Calcium Fluoride

Note: A metal is a solid(s) and powder is a solid(s). A gas is denoted as (g). They depict the state of the species reacting.

                    F₂_{(g)}     +    Ca_{(s)}               →           CaF₂_{(s)}

We can see that equal number of atoms are on both sides of the expression.

7 0
2 years ago
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arsen [322]
Slow chemical change

It is a chemical change because the erosion is due to the chemical reaction between the acid and the in the rain and the calcium carbonate.

It is slow due to the concentration of acid is low.
3 0
2 years ago
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