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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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1. A neutral atom has a mass number of 108 and an atomic number of 47.
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A. Silver

Proton- 47
Electrons- 47
Neutron- 61

108-47=61
8 0
4 years ago
Classify each titration curve as representing a strong acid titrated with a strong base, a strong base titrated with a strong ac
Ilya [14]

Answer:

Acid base titration curves shows the pH at equivalence point

Explanation:

Since the images were not shown, I will proceed to give a general description of the following acid-base titration curves:

In a strong acid-strong base titration, the acid and base will react to form a neutral solution. At the equivalence point of the reaction, hydronium (H+) and hydroxide (OH-) ions will react to form water, leading to a pH of 7.

The titration curve reflects the strengths of the corresponding acid and base. If one reagent is a weak acid or base and the other is a strong acid or base, the titration curve is irregular, and the pH shifts less with small additions of titrant near the equivalence point.

Polyprotic acids are able to donate more than one proton per acid molecule, in contrast to monoprotic acids that only donate one proton per molecule. In the titration curve of a polyptotic acid and a strong base, The curve starts at a higher pH than a titration curve of a strong base. There is always a steep climb in pH before the first midpoint. Gradually, the pH increases until it passes the midpoint; Right before the equivalence point there is a very sharp increase in pH.

3 0
3 years ago
KClO₃ → Kelt Oz
cestrela7 [59]

Answer:

5.2 moles of  KClO₃  are needed

Explanation:

Given data:

Number of moles of potassium chlorate needed = ?

Number of moles of O₂ formed = 7.8 mol

Solution:

Chemical equation:

2KClO₃      →     2KCl + 3O₂

now we will compare the moles of KClO₃ and  O₂.

                   O₂        :         KClO₃    

                    3          :           2

                   7.8        :          2/3×7.8 = 5.2

5.2 moles of  KClO₃  are needed.

5 0
3 years ago
D. liquid
erastovalidia [21]

Answer: H2O

Explanation: The given balanced chemical reaction is,

This reaction is a reversible reaction.

The rate of forward reaction will be,

The rate of backward reaction will be,

And at equilibrium the rate of reaction is equal to the rate of backward reaction divided by the rate of forward reaction.

4 0
3 years ago
What is the effect of high activation energy on a chemical reaction?
sweet [91]

D. It makes the reaction harder to start- the need for more activation energy means less successful collisions therefore the reaction can not be started as easily if there were a lower activation energy.

3 0
3 years ago
Read 2 more answers
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