If we consider a combustion reaction of Methane:
The balanced equation is:
CH4 + 2O2 ---> 2H2O + CO2
The rate of appearance of H2O is rH2O, rate of disappearance of O2 is -rO2
(rH2O)^2 = (-rO2)^2
rH2O = -rO2
What intermolecular forces are present in each of the substances? CH4,C3H8,CH3F,HF, C6H5OH (dispersion forces<span>, </span>dipole-dipole forces<span>, or </span>hydrogen bonding<span>);A sample of ideal gas at room temperature occupies a volume of 34.0L at a pressure of 782torr .</span>
A) 2H₂(g) + O₂(g) → 2H₂O(l) + 285.83 kJ
Exothermic
B) 2Mg + O₂ → 2MgO + 1200kJ
Exothermic
<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
Your answer would be,
Molarity = moles of solute/volume of solution we needed, 29.22(g)(mol) of NaCI
= 29.22(g)/58.44(g)(mol^-1)(1)/1(L)
= 0.500(mol)(L^-1)
Hope that helps!!!
