topic 2: amount of substance

Question 1

ideal gas equation

Answer 1

pV= n RT

Question 2

temperature into kelvins

Answer 2

+273

Question 3

m3 —> dm3 —> cm3

Answer 3

m3—-> dm3 (x1000)
dm3—-> cm3 (x1000)
m3—–> cm3 (x1000000)
cm3—–>dm3 (divide by 1000)
dm3—–> m3 (divide by 1000)
cm3—->m3 (divide by 1000000)

Question 4

percentage atom economy

Answer 4

(molecular mass of desired product/ sum of molecular masses of all reactants) x 100

Question 5

what is atom economy?
why is a higher atom economy desirable?

Answer 5

-atom economy is a measure of the efficiency of a reaction

in industrial processes, it is desirable to have a high atom economy for a reaction:

-this means there is little or no waste products, only the desired product

Question 6

atom economy benefits for the environment and economy

Answer 6

-processes with high atom economy is more economically viable in the chemical industry
-environmentally friendly, less waste produced and less energy used
-more efficient use of raw materials, so they are more sustainable

Question 7

moles formula

Answer 7

mass= moles x Mr
moles= volume x concentration

Question 8

percentage yield

Answer 8

(actual mass produced/ theoretical mass) x 100

Question 9

what is percentage yield?

Answer 9

-the percentage yield tells us how efficient the process was of which reactants are converted into products and how much was lost by practical process of obtaining a product

-theoretical yield: mass of product that should be formed in a chemical reaction
-actual mass: less than the theoretical yield

Question 10

causes of a lower percentage yield

Answer 10

-due to incomplete reactions
-side reactions
-loss in of product in transfer