Just find the percent mass of oxygen in sucrose again. and then multiply that by 50.00.
The molarity of a 27%(v/v) aqueous ethanol solution is 4.63 M
calculation
convert 27%(v/v) to fraction = 27ml/100 ml
use density to convert 27ml to grams = 27 ml x0.79 g/ml = 21.33 g
find the number of moles of C2H6O
moles = mass/molar mass of C2H6O(46.07 g/mol)
moles is therefore = 21.33 g /46.07 g/mol =0.463 moles
find the molarity = moles /volume in liters
volume in liter = 100 ml/1000 = 0.1 L
molarity is therefore = 0.463 mole/0.1 L = 4.63 M
Answer:
The enthalpy change of the reaction is -66.88 kJ/mol.
Explanation:
Mass of the solution = m = 100 g
Heat capacity of the solution = c = 4.18 J/g°C
Initial temperature of the solutions before mixing = 
Final temperature of the solution after mixing = 
Heat gained by the solution due to heat released by reaction between HCl and silver nitrate = Q


Heat released due to reaction = Q' =-Q = -334.4 J
Moles of silver nitrate = n
Molarity of silver nitrate solution = 0.100 M
Volume of the silver nitrate solution = 50.0 mL = 0.050 L ( 1 mL = 0.001 L)


Enthalpy change of the reaction = 

1 J = 0.001 kJ
The enthalpy change of the reaction is -66.88 kJ/mol.
Mole =mass ÷ Mr
∴mass = mole×Mr =0.10 × (23+35.5) = 5.85
the answer is D...
The Mr is obtained from the periodic table