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pav-90 [236]
3 years ago
7

g When 2.50 g of methane (CH4) burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion (in kJ) per mole

of methane under these conditions
Chemistry
1 answer:
Anna [14]3 years ago
3 0

Answer:

-800 kJ/mol

Explanation:

To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).

First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:

Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol

moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄

Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:

ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol

Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).

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Which of the following are held together by nonpolar convalent bonds?
Olin [163]

A. Atoms of chlorine (Cl)

Explanation:

The atoms of chlorine are held together by non-polar covalent bonds.

  • Covalent bonds are formed between two or more atoms having zero or very small electronegativity difference.
  • For homonuclear molecules where the two bonding atom are of the same kind, the electronegativity difference is zero.
  • This covalent bond type is called non-polar covalent bond.
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6 0
3 years ago
A solution is made by dissolving
barxatty [35]

Answer:

4.52 mol/kg

Explanation:

Given data:

Mass of lithium fluoride = 22.1 g

Mass of water = 188 g

Molality = ?

Solution:

Molality:

It is the number of moles of solute into kilogram of solvent.

Formula:

Molality = number of moles of solute / kilogram solvent

Mathematical expression:

m = n/kg

Now we will convert the grams of LiF into moles.

Number of moles = mass/ molar mass

Number of moles = 22.1 g/ 26 g/mol

Number of moles = 0.85 mol

Now we will convert the g of water into kg.

Mass of water = 188 g× 1kg/1000 g = 0.188 kg

Now we will put  the values in formula.

m = 0.85 mol / 0.188 kg

m = 4.52 mol/kg

8 0
3 years ago
Cubic zirconia is a substance produced in a laboratory. It looks nearly identical to a diamond. Why is it not a mineral?
Lana71 [14]

Answer:

it is not naturally occuring

5 0
3 years ago
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3. In an experiment it was found that 40.0cm of 0.2M sodium hydroxide solution just neutralized 0.2g
hjlf

The relative molecular mass of acid A : 50 g/mol

<h3>Further explanation</h3>

Given

40.0 cm³(40 ml) of 0.2M sodium hydroxide

0.2g  of a dibasic acid

Required

the relative molecular mass of acid A

Solution

Titration formula

M₁V₁n₁=M₂V₂n₂

n=acid/base valence(number of H⁺/OH⁻)

NaOH ⇒ n = 1

Dibasic acid =  diprotic acid (such as H₂SO₄)⇒ n = 2

mol = M x V

Input the value in the formula :(1 = NaOH, 2=dibasic acid)

0.2 x 40 x 1 = M₂ x V₂ x 2

M₂ x V₂ = 4 mlmol = 4.10⁻³ mol ⇒ mol of Acid A

The relative molecular mass of acid A (M) :

\tt M_A=\dfrac{mass }{mol}=\dfrac{0.2~g}{4.10^{-3}}=50~g/mol

5 0
3 years ago
Which is not an issue with waste from nuclear energy?
Mkey [24]

Answer:

correct option is A) atmospheric pollutants

Explanation:

  • Nuclear power plant do not produce air pollution in the form of carbon dioxide and sulfur dioxide.
  • Nuclear as radioactive waste is hazardous to all kind of life and the environment.
  • Long-term storage of radioactive waste is required. It is important that waste stabilization is a form that does not react or deteriorate for years.
  • If nuclear waste is wasted in the atmosphere or in the oceans and lagre lakes, it eventually comes into contact with organisms.
3 0
3 years ago
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