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Zolol [24]
3 years ago
12

A sample of gold (Au) has a mass of 45.39 g.

Chemistry
1 answer:
professor190 [17]3 years ago
8 0
<span>1. What is the molar mass of gold?
Molar mass is a unit that expresses the mass of a molecule per one mol. The molar mass can be obtained by adding the neutron with the proton of the atoms. Gold has atomic number 79 so the proton is 79. The number of the neutron is 118. Then the molar mass would be: 79 + 118 = </span>197 g/mol<span>


</span><span>2. Calculate the number of moles of gold (Au) in the sample. Show your work. 
</span>In this question, you are given the mass of the gold and asked for how many moles the sample has. To find the number of moles you just need to divide the weight by the molar mass.
For 45.39 grams of gold, the number of moles would be:
45.39 / (197g/mol)= 0.23 moles


3. Calculate the number of atoms of gold (Au) in the sample. Show your work.Moles is unit of a number of molecules but 1 mol doesn't represent 1 molecule. The number of atoms can be obtained by multiplying the number of moles with Avogadro number. The calculation would be:
0.23 moles * (6.023 * 10^23 molecules/mol)= 1.387 * 10^23 molecules
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Arrange the following oxides in order of increasing acidity.
zmey [24]

Answer:

Based on the Modern Periodic table, there is an increase in the electropositivity of the atom down the group as well as increases across a period. On comparing the electropositivities of the mentioned oxides central atom, it is seen that Ca is most electropositive followed by Al, Si, C, P, and S is the least electropositive.  

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5 0
3 years ago
If a buffer solution is 0.130 M in a weak acid (K_a = 1.7 x 10^-5) and 0.590 M in its conjugate base, what is the pH?
Serggg [28]
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8 0
3 years ago
What is the molarity of a solution that contains 0.082 mol KI in a 2.03 L solution?
astraxan [27]

Answer:

molarity of the KI solution = 0.04 mol/L

Explanation:

Molarity (M) is the concentration of a solution expressed as the number of moles of solute per liter of solution.  

The law that we can applied to calculate the M is:  

M = n / V

n - number of moles

V- volume of the solution (liters)

Then insert in the equation the values from the question;  

M = 0.082 mol  /  2.03 L = 0.04 mol/L

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3 years ago
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