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3 years ago

How many grams of calcium hydride are needed to form 4.550 g of hydrogen gas

1 answer:

4 0

Molar mass

CaH₂ = 42.0 g/mol

H₂ = 2.0 g/mol

Balanced chemical equation :

CaH2 + 2 H₂O = Ca(OH)₂ + 2 H₂

42.0 g CaH₂ --------------------- 4.0 g H2
? g CaH₂ ---------------------- 4.550 g H2

mass = 4.550 * 42.0 / 4

mass = 191,1 / 4

mass = 47.775 g of CaH₂

hope this helps!

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What does X represent for this transmutation?

Dimas [21]

Answer:

24He

Explanation:

When a nuclide is bombarded with alpha particles, we notice an increase in its mass and charge since an alpha particle has a mass of four and a charge of +2. recall that nuclear equations must be balanced. That is, the masses and charges on the left hand six and the right hand side of the nuclear reaction equation must be exactly the same.

Looking at the nuclear reaction at hand, the total mass on the left hand side has to be 246 while the total charge on the left hand side of the equation will be 98. Coming over to the right hand side, the total masses are also found to be the same as a neutron with no charge and a mass of 1 is produced. Hence the nuclear reaction equation is balanced when an alpha particle (helium nucleus) is substituted for X in the equation.

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3 years ago

What coefficient is assumed if no coefficient written before a formula in a chemical equation

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Answer:

Explanation:

Consider the following reaction:

Phosphorus burn in the presence of air and produced diphosphorus pentoxide.

Chemical equation:

P₄ + O₂ → P₂O₅

Balanced chemical equation:

P₄ + 5O₂ → 2P₂O₅

Equation is balanced because there are four phosphorus atoms ans ten oxygen atoms in both side of equation.

Coefficient with reactant and product:

P₄ 1

O₂ 5

P₂O₅ 2

There is no coefficient written before P₄ it means only one P₄ is present.

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4 years ago

For which blocks of elements are outer electrons the same as valence electrons? For which are d electrons often included among v

Amanda [17]

Answer:

1. Group 1 — 3

2. Transition metals

Explanation:

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4 years ago

What happens inside an atom that causes it to give off light?

Umnica [9.8K]

The Photon is the "release" of energy in the form of light. Energy absorbed by the atom causes a change in energy of the electrons of a stable atom. This change forces an electron to move from one valance ring to another. The energy is released in the form of light called a photon. Depending on the amount of energy released and the valance the electron jumps to is what determines the light (photon) wave length. If an atom has too much light than it may disappear/explode.

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3 years ago

Determine the oxidation number of Cl in each of the following species.Cl2O7AlCl4-Ba(ClO2)2CIF4+

DIA [1.3K]

These are four questons and four answers:

Answers:

1) 7⁺

2) 1⁻

3) 3⁺

4) 5⁺

Explanation:

Question 1) Cl₂O₇:

a) Net charge of the compound: 0

b) Rule: oxygen works with oxidation state +2, except with peroxides.

d) Rule: balance of charges: ∑ of the charges = net charge

Call X the oxidation number of Cl:

2×X + 7 (-2) = 0

2X - 14 = 0

2X = +14

X = +14 /2 = + 7

Conclusion: the oxidation number of Cl in Cl₂O₇ is 7⁺.

Question 2) AlCl₄⁻

a) Net charge of the ion: - 1

b) Rule: common oxidation number of Al in compounds: +3

c) Rule: balance of charges: ∑ charges = net charge = - 1

1 (+3) + 4X = - 1

+3 + 4X = - 1

4X = - 1 - 3

4X = - 4

X = - 1

Conclusion: the oxidation number of Cl in AlCl₄⁻ is 1 ⁻.

Question 3) Ba(ClO₂)₂

a) Net charge of the compound: 0

b) Rule: common oxidation number of BA in compounds: +2

c) Rule: common oxidation number of O in compounds (except in peroxides): -2

d) Rule: balance of charges: ∑ charges = net charge = 0

+2 + 2X + 4 (-2) = 0

2X +2 - 8 = 0

2X - 6 = 0

2X = +6

X = + 3

Conclusion: the oxidation number of Cl in Ba(ClO₂)₂ is 3⁺.

Question 4) CIF₄⁺

a) Net charge of the ion: + 1

b) Rule: common oxidation number of F : - 1 (it is the most electronegative)

c) Rule: balance of charges: ∑ charges = net charge = + 1

X + 4(-1) = +1

X - 4 = +1

X = +1 + 4

X = + 5

Conclusion: the oxidation number of Cl in ClF₄⁺ is 5⁺.

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3 years ago