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wolverine [178]
3 years ago
11

4.5 × 1025 atoms of nickel equal how many moles? A. 27 mol B. 2.7 × 1048 mol C. 0.75 mol D. 75 mol

Chemistry
2 answers:
crimeas [40]3 years ago
7 0

Answer:

75 mol

Explanation:

The number of atoms in a mole of substance is 6.023X10²³ [Avagadro's number]

if the given sample of nickel contains 4.5X10²⁵ atoms it means the moles are

moles = \frac{numberofatoms}{Avagadro'snumber}

moles = \frac{4.5X10^{25}}{6.023X^{23}}=74.71mol

If we round of the given answer the number of moles = 75 moles

Molodets [167]3 years ago
4 0
It's 75
PS use ^ to mean to the power of
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. How many milliliters of 0.20 M HCl are needed to exactly neutralize 40. milliliters of 0.40 M KOH
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Answer:

V_{HCl}=80mL

Explanation:

Hello,

In this case, for the given reactants we identify the following chemical reaction:

KOH+HCl\rightarrow KCl+H_2O

Thus, we evidence a 1:1 molar ratio between KOH and HCl, therefore, for the complete neutralization we have equal number of moles, that in terms of molarities and volumes become:

n_{HCl}=n_{KOH}\\\\M_{HCl}V_{HCl}=M_{KOH}V_{KOH}

Hence, we compute the volume of HCl as shown below:

V_{HCl}=\frac{M_{KOH}V_{KOH}}{M_{HCl}} =\frac{0.40M*40mL}{0.20M} \\\\V_{HCl}=80mL

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5 0
3 years ago
What is the pH of a 0.0042 M hydrochloric acid solution?
babymother [125]

Answer:

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Explanation:

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i.e. ,

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and ,

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pH is given as the negative log of the concentration of H⁺ ions ,

hence ,

pH = - log H⁺

From the question ,

the concentration of the solution is 0.0042 M , and being it a strong acid , dissociates completely to its respective ions ,

Therefore , the concentration of H⁺ = 0.0042 M .

Hence , using the above equation , the value of pH can be calculated as follows -

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pH = - log ( 0.0042 M )

pH =  2.38 .

4 0
4 years ago
A particular voltaic cell operates with the reaction: Zn(s)+Cl2(g)--->Zn^2+(aq)+2Cl^-(aq) giving a cell potential of .853 V.
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Answer:

The amount of energy liberated will be 49.38 J.

Explanation:

The amount of energy liberated (gibbs free energy) can be calculated using the following equation:

ΔG° = -nFε

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F: Faraday's constant

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20.0 g of Zn is equal to 0.30 mol.

Two electrons are transfered during the reaction.

Therefore, n = 2x0.30 ∴ n = 0.60

ΔG° = - 0.60 x 96.485 x 0.853

ΔG° = 49.38 J

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The answer is d, hand soap.

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