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Black_prince [1.1K]
3 years ago
9

40o+2 protons electrons And neurons

Chemistry
1 answer:
KatRina [158]3 years ago
7 0

Answer: There are few simple rules to follow.

(1) The atomic number is equal to the number of protons.

Z

= number of protons

(2) In neutrally charged elements, the number of electrons is the same as the number of protons.  

Z

= number of protons = number of electrons (no charge)

Otherwise, positive charge means that the element lost an electron and negative charge means it gained an electron.

(3) The atomic mass is equal to the sum of the number of protons and number of neutrons.

A

= number of protons + number neutrons  

or

A

=  

Z

+ number neutrons

So if you say that  

Z

= 20 and  

A

= 40, then

A

=  

Z

+ number neutrons

40 = 20 + number of neutrons

40 - 20 = number of neutrons

Therefore,

number of neutrons = 20

Explanation:

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(a) ions in a certain volume of .20M NaCl (aq) are represented in the box above on the left. in the box above on the right, draw
mamaluj [8]

Answer:

  • The first picture attached is the diagram that accompanies the question.

  • The<u> second picture attached</u> is the diagram with the answer.

Explanation:

In the box on the left there are 8  Cl⁻ ions and 8 Na⁺ ions.

The dissociaton equation for NaCl(aq) is:

  • NaCl (aq) → Na⁺ (aq) + Cl⁻(aq)

The dissociation equation for CaCl₂ (aq)  is:

  • CaCl₂ (aq) → Ca²⁺ (aq) + 2Cl⁻(aq)

A 0.10MCaCl₂ (aq) solution will have half the number of CaCl₂ units as the number of NaCl units in a 0.20M NaCl (aq) solution.

Thus, while the 0.20M NaCl (aq) solution yields 8 ions of Na⁺ and 8 ions of Cl⁻, the 0.10MCaCl₂ (aq) solution will yield 4 ions of Ca²⁺ (half because the concentration if half)  and 8 ions of Cl⁻ (first take half and then multiply by 2 because the dissociation reaction).

Thus, your drawing must show 4 dots representing Ca²⁺ ions and 8 dots representing Cl⁻ ions in the box on the right.

4 0
3 years ago
What is the molar mass of Al2(SO4)3
Allisa [31]

342.15 g/mol is the molar mass of Al2(SO4)3 Aluminium sulfate, This is what I found I hope this is right. Hope this helps;)

5 0
3 years ago
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Đốt cháy hết 9g kim loại magie Mg trong không khí tích tụ được 15g hợp chất magie oxit MgO. Biết rằng magie cháy là xảy ra phản
vfiekz [6]

Answer:

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Explanation:

kjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj

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Calculate the molarity of 29.0g of ethanol (C2H5OH) in 545 mL of solution.
BigorU [14]
Molar mass ethanol:

C2H5OH = 12 x 2+ 1 x 5 + 16  + 1 =  46.0 g/mol

volume = 545 mL in liters: 545 / 1000 => 0.545 L

number of moles:

29.0 / 46.0 => 0.6304 moles

M = n / V

M = 0.6304 / 0.545

M = 1.156 mol/L

hope this helps!


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3 years ago
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Five kilograms of liquid carbon tetrachloride undergo a mechanically reversible, isobaric change of state at 1 bar during which
Drupady [299]

Answer:

Explanation:

From the information given:

Mass of carbon tetrachloride = 5 kg

Pressure = 1 bar

The given density for carbon tetrachloride = 1590 kg/m³

The specific heat of carbon tetrachloride =  0.84 kJ/kg K

From the composition, the initial volume of carbon tetrachloride will be:= \dfrac{5 \ kg }{1590 \ kg/m^3}

= 0.0031 m³

Suppose \beta is independent of temperature while pressure is constant;

Then:

The change in volume can be expressed as:

\int ^{V_2}_{V_1} \dfrac{dV}{V} =\int ^{T_2}_{T_1} \beta dT

In ( \dfrac{V_2}{V_1})  = \beta (T_2-T_1)

V_2 = V_1 \times exp (\beta (T_2-T_1))

V_2 = 0.0031 \ m^3  \times exp  (1.2 \times 10^{-3} \times 20)

V_2 = 0.003175 \ m^3

However; the workdone = -PdV

W = -1.01 \times 10^5 \ Pa \times ( 0.003175 m^3 - 0.0031 \ m^3)

W = - 7.6 J

The heat energy Q = Δ h

Q = mC_p(T_2-T_1)

Q = 5 kg \times 0.84 \ kJ/kg^0 C \times 20

Q = 84 kJ

The internal energy is calculated by using the 1st law of thermodynamics; which can be expressed as;

ΔU = ΔQ + W

ΔU = 84 kJ + ( -7.6 × 10⁻³ kJ)

ΔU = 83.992 kJ

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3 years ago
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