Mass percentage is defined as the ratio of mass of the element to the total mass of the compound.
The formula of mass percentage is given by:
Mass percentage = 
(1)
mass of nitrogen = 56.00 grams
Let x be the total mass of the compound.
Put the given values in formula (1):
x= 
x= 151.92 g
total mass of the compound = 151.92 g
To calculate the mass of oxygen in grams, subtract the mass of nitrogen from the total mass of the compound.
Mass of oxygen = 151.92 g - 56 .00 g = 95.92 g
Thus, mass of oxygen in grams = 95.92 grams.
1st one is Science and the 2nd one is Bias
Answer : The molar heat of solution of KBr is 19.9 kJ/mol
Explanation :
Mass of KBr = 7.00 g
Molar mass of KBr = 119 g/mole
Heat capacity = 2.72 kJ/K
Change in temperature = 0.430 K
First we have to calculate the moles of KBr.
Now we have to calculate the heat of the reaction.
where,
q = amount of heat = ?
= heat capacity = 
= change in temperature = 0.430 K
Now put all the given values in the above formula, we get:
Now we have to calculate the molar heat of solution of KBr.
where,
n = number of moles of KBr
Therefore, the molar heat of solution of KBr is 19.9 kJ/mol
Answer:
Molality = 0.43 m
Explanation:
Given data:
Mass of barium sulfide = 25.4 g
Mass of water = 349 g (349 g/1000 = 0.349 Kg)
Molality of water = ?
Solution:
Number of moles of barium sulfide:
Number of moles = mass/molar mass
Number of moles = 25.4 g/169.39 g/mol
Number of moles = 0.15 mol
Molality:
Molality = number of moles o f solute/ Kg of solvent
Molality = 0.15 mol / 0.349 Kg
Molality = 0.43 m
