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dangina [55]
3 years ago
14

How many moles of potassium are in 3.78 x 10^21 atoms of K?

Chemistry
1 answer:
lbvjy [14]3 years ago
3 0

Answer: 6.3 x 10^-3 moles

Explanation:

Based on Avogadro's law:

1 mole of any substance has 6.02 x 10^23 atoms

So, 1 mole of potassium = 6.02 x 10^23 atoms

Z moles = 3.78 x 10^21 atoms

To get the value of Z, we cross multiply:

(3.78 x 10^21 atoms x 1mole) = (6.02 x 10^23 atoms x Z moles)

3.78 x 10^21 = (6.02 x 10^23 x Z)

Z = (3.78 x 10^21) ➗ (6.02 x 10^23)

Z = 0.63 x 10^-2)

Place the result in standard form

Hence, Z = 6.3 x 10^-3 moles

Thus, there are 6.3 x 10^-3 moles of potassium in 3.78 x 10^21 atoms of K.

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Citrus2011 [14]
25/2 and 96/X
CROSS MULTIPLY.

2x=2,400.
divide by 2.
x=1,200.

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3 0
3 years ago
Calculate the mass, in grams, of Ag2CrO4 that will precipitate when 50.0mL of 0.20M AgNO3 solution is mixed with 40.0mL of 0.10M
Darina [25.2K]

Answer:

1.327 g Ag₂CrO₄

Explanation:

The reaction that takes place is:

  • 2AgNO₃(aq) + K₂CrO₄(aq)  → Ag₂CrO₄(s) + 2KNO₃(aq)

First we need to <em>identify the limiting reactant</em>:

We have:

  • 0.20 M * 50.0 mL = 10 mmol of AgNO₃
  • 0.10 M * 40.0 mL = 4 mmol of K₂CrO₄

If 4 mmol of K₂CrO₄ were to react completely, it would require (4*2) 8 mmol of AgNO₃. There's more than 8 mmol of AgNO₃ so AgNO₃ is the excess reactant. <em><u>That makes K₂CrO₄ the limiting reactant</u></em>.

Now we <u>calculate the mass of Ag₂CrO₄ formed</u>, using the <em>limiting reactant</em>:

  • 4 mmol K₂CrO₄ * \frac{1mmolAg_2CrO_4}{1mmolK_2CrO_4} *\frac{331.73mg}{1mmolAg_2CrO_4} = 1326.92 mg Ag₂CrO₄
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7 0
3 years ago
Calculate the number of chlorine atoms that are present in 66.05 g of dichloromethane, ch2cl2. when you have the number, take it
Whitepunk [10]
From the periodic table:
mass of carbon = 12 grams
mass of hydrogen = 1 gram
mass of chlorine = 35.5 grams
Therefore,
molar mass of CH2Cl2 = 12 + 2(1) + 2(35.5) = 85 grams

number of moles = mass / molar mass
number of moles of CH2Cl2 = 66.05 / 85 = 0.777 moles

One mole of CH2Cl2 contains two moles of Cl and each chlorine mole has Avogadro's number of atoms in it.
Therefore,
number of chlorine atoms in 0.777 moles of CH2Cl2 can be calculated as follows:
number of atoms = 0.777 * 2 * 6.022 * 10^23 = 9.358 * 10^23 atoms

Now, we will take log base 10 for this number:
log (9.358 * 10^23) = 23.97119
5 0
3 years ago
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valentina_108 [34]
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3 years ago
Analyzing a specific reaction Consider the following reaction: 2Mg+O2→2MgO,rate=k[Mg][O2]2 Part A What is the overall reaction o
stepladder [879]

Answer:

3

Explanation:

Order of in the mass action law is the coefficient which is raised to the active concentration of the reactants. It is experimentally determined and can be zero, positive negative or fractional.

The order of the whole reaction is the sum of the order of each reactant which is raised to its power in the rate law.

Thus,

For the reaction:-

2Mg+O₂→2MgO

Rate  = k[Mg][O₂]²

Order w.r.t. Mg = 1

Order w.r.t. O₂ = 2

<u>So, order of the overall reaction = 1 + 2 = 3</u>

7 0
3 years ago
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