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3 years ago

PLS HELP THE QUESTION IS ON THE PICTURE

Chemistry

1 answer:

IceJOKER [234]3 years ago

3 0

Concepts used:

1 mole of an element or a compound has 6.022 * 10²³ formula units

So, we can say that: Number of formula units = number of moles * 6.022*10²³

number of moles of an element or a compound = given mass/molar mass

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003 - Number of CaH₂ formula units in 6.065 grams

Number of Moles:

We know that the molar mass of CaH₂ is 42 grams/mol

Number of Moles of CaH₂ = given mass/molar mass

Number of moles = 6.065 / 42

Number of moles = 0.143 moles

Number of Formula units:

Number of formula units = number of moles * 6.022*10²³

= 0.143 * 6.022 * 10²³

= 0.86 * 10²³ formula units

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004 - Mass of 6.34 * 10²⁴ formula units of NaBF₄

Number of Moles:

We mentioned this formula before:

Number of formula units = number of moles * 6.022*10²³

Solving it for number of moles, we get:

Number of moles = Number of Formula units / 6.022* 10²³

replacing the variable

Number of moles = 6.34 * 10²⁴ / 6.022*10²³

Number of moles= 10.5 moles

Mass of 10.5 moles of NaBF₄:

Molar mass of NaBF₄ = 38 grams/mol

Mass of 10.5 moles = 10.5 * molar mass

Mass of 10.5 moles = 10.5 * 38

Mass = 399 grams

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005 - Number of moles in 9.78 * 10²¹ formula units of CeI₃

Number of Moles:

We have the formula:

Number of moles = Number of Formula units / 6.022* 10²³

replacing the variables

Number of Moles = 9.78 * 10²¹ / 6.022*10²³

Number of Moles = 1.6 / 10²

Number of Moles = 1.6 * 10⁻² moles OR 0.016 moles

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Explanation:

If we have the following reaction at equilibrium:

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where Kc is the equilibrium constant, which holds that for a reversible reaction at equilibrium and a constant temperature, a certain ratio of reactant and product concentrations has a constant value, Kc (the equilibrium constant). Note that although the concentrations may vary, as long as the reaction in in equilibrium and temperatura don't change, the value of K remains constant.

For reactions that have not reached equilibrium, we obtain the reaction quotient (Qc), instead of the equilibrium constant by substituting the initial concentrations into the equilibrium constant expression.

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To determine the direction in wich the net reaction will proceed to reach equilibrium, que compare the values of Qc and Kc.

Qc < Kc: To reach equilibrium, reactants must be converted to products (→)
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Solution:

We have the following reaction:

NO2Cl(g)+NO(g)⇌NOCl(g)+NO2(g)

So:

Kc=([NOCl]^1*[NO2]^1)/([NO2Cl]^1 *[NO]^1)

=([NOCl][NO2])/([NO2Cl][NO])

1. In the equation above, [NO2Cl] it's in the denominator, so if we increase it's numericall value by adding NO2Cl decreases Qc to a value less than Kc.

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2. To reach a new state of equilibrium (where Qc = Kc), Qc therefore increases wich means that the denominator of the expression for Qc decreases (in order to increase the denominator as mention above).

3. To accomplish this, the concentration of reageants decreases (reagents are being consumed), and the concentration of prodcuts increases (products are being formed).

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