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Natalija [7]
2 years ago
15

Can someone answer these for me I’ll mark you brainliset or whatever it’s called lol I rlly need to get these right

Chemistry
1 answer:
aleksandrvk [35]2 years ago
7 0
Gg rjhrrjfnrjrkrkrkrjjtjrrkrktotofofovkfjiffiifi
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A sample of gold (Au) has a mass of 45.39 g.
professor190 [17]
<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
8 0
3 years ago
What is the concentration of no3- ions in a solution prepared by dissolving 15.0 g of ca(no3)2 in enough water to produce 300. m
r-ruslan [8.4K]

Ca(NO3)2 -------> Ca²⁺ +2NO3⁻

M(Ca(NO3)2)= M(Ca) + M(N) + 6M(O)= 40.0 +14.0 +6*16.0 = 150 g/mol

15.0 g Ca(NO3)2 * 1mol/150 g = 0. 100 mol Ca(NO3)2


Ca(NO3)2 -------> Ca²⁺ +2NO3⁻
1 mol                               2 mol
0.100 mol                           0.200 mol

We have 0.2 mol NO3⁻ in 300. mL=0.300 L of solution,
so
0.200 mol NO3⁻ / 0.300 L solution ≈ 0.667 mol NO3⁻ /L solution = 0.667 M

Concentration of NO3⁻ is 0.667 M.



4 0
3 years ago
Which of the four cars had the least net force applied to it when it was launched down the ramp
castortr0y [4]

The least net force applied : Car 3(12 N)

<h3>Further explanation  </h3>

Newton's 2nd law explains that the acceleration produced by the resultant force on an object is proportional and in line with the resultant force and inversely proportional to the mass of the object  

∑F = m. a  

Car 1 ⇒m=0.5 kg, a=36 m/s²

\tt \sum F=0.5\times 36=18~N

Car 2⇒m=0.8 kg, a=50 m/s²

\tt \sum F=0.8\times 50=40~N

Car 3⇒m=0.6, a=20 m/s²

\tt \sum F=0.6\times 20=12~N

Car 4⇒m=1, a=19~m/s²

\tt \sum=1\times 19=19~N

5 0
2 years ago
When the mixture was moved from room temperature to a higher temperature, the mixture turned darker brown. Which of the followin
Wittaler [7]

Answer:

The equilibrium between the two forms of the gas is disturbed at high temperatures.

7 0
2 years ago
Why is foam fight chemical or a physical change
nata0808 [166]

Answer:

Foam fight is a chemical change.

Explanation:

Please give me brainliest :)

4 0
3 years ago
Read 2 more answers
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