Answer:
Explanation:
The formula for molality is:
There are 0.210 moles of KBr and 0.075 kilograms of pure water.
Substitute the values into the formula.
Divide.
The molality is <u>2.8 moles per kilogram</u>
4 Identify Give an example of a physical change and an example of a chemical change.
1 answer:
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Answer :
(a) 1.000 g of compound containing carbon and hydrogen is, 0.922 g and 0.0769 g respectively.
(b) There is no other element present in the compound.
Explanation :
(a) Now we have to determine the masses of C and H in the sample.
The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:
where, 'x' and 'y' are the subscripts of Carbon and hydrogen respectively.
We are given:
Mass of
Mass of
We know that:
Molar mass of carbon dioxide = 44 g/mol
Molar mass of water = 18 g/mol
For calculating the mass of carbon:
In 44 g of carbon dioxide, 12 g of carbon is contained.
So, in 3.381 g of carbon dioxide, of carbon will be contained.
For calculating the mass of hydrogen:
In 18 g of water, 2 g of hydrogen is contained.
So, in 0.692 g of water, of hydrogen will be contained.
Thus, 1.000 g of compound containing carbon and hydrogen is, 0.922 g and 0.0769 g respectively.
(b) Now we have to determine the compound contain any other elements or not.
Mass carbon + Mass of hydrogen = 0.922 g + 0.0769 g = 0.999 g ≈ 1 g
This means that there is no other element present in the compound.
Answer: a. 79.6 s
b. 44.3 s
c. 191 s
Explanation:
Expression for rate law for first order kinetics is given by:
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
b) for completion of 32% of reaction
c) for completion of 81 % of reaction