ΔH(reaction) = ΔH(formation of products) - ΔH(formation of reactants)
ΔH(reaction) = ( 1*ΔH(Pb(s)) + 1*ΔH(CO2(g)) ) - ( 1*ΔH(PbO(s)) + 1*ΔH(CO(g)) )
ΔH(reaction) = ( 0 + -393.5 ) - ( ΔH(PbO(s)) + -110.5 )
ΔH(reaction) = -283 - ΔH(PbO(s))
-131.4 = -283 -ΔH(PbO(s))
ΔH(PbO(s)) = -151.6 kJ
So, the best answer is A.
First, let's determine the number of moles of carbon atoms by using molar mass. Then, using Avogadro's number, we can find the number of C atoms:
*1 mole of C3H8O= (12.0x3)+(1.0x8)+(16.0x1) = 60.0g/mol
25.0 grams C3H8O x (1 mole C3H8O/60.0 grams) = 0.417 mol
0.417mol C3H8O has (3 x 0.417 moles) C atoms = 1.251 moles C atoms
1.251 moles C atoms x(6.022x10^23 atoms/mol) = 9.42x10^23 C atoms.
The answer is in 3 significant figures, as that's what we have in the given, and we matched it with our rounding of the atomic masses from the periodic table.
You can do this all in one equation written left to right, just exclude the intermediate answers. Just easier to show it this way on the computer screen.
Answer: The empirical formula for the given compound is 
Explanation : Given,
Percentage of C = 84.4 %
Percentage of H = 15.6 %
Let the mass of compound be 100 g. So, percentages given are taken as mass.
Mass of C = 84.4 g
Mass of H = 15.6 g
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.
Moles of Carbon =
Moles of Hydrogen = 
Step 2: Calculating the mole ratio of the given elements.
For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.03 moles.
For Carbon = 
For Hydrogen = 
Step 3: Taking the mole ratio as their subscripts.
The ratio of C : H = 1 : 2
Hence, the empirical formula for the given compound is 
Answer:
Explanation:
70% (vol/vol) means
cotnaimns 70 %(vol/vol) 70 ml of isoprapnol is there in 100 ml of Rubbing sold alcohol.
if it is 200 ml then obvouly it has the 70*2 =140 ml of isoproanol required.
