Chemistry - things that need polishing

Question 1

What is the bond angle in pyramidal molecules?

Answer 1

107o

Question 2

In what circumstances do molecules have a pyramidal shape?

Answer 2

Three bonded pairs of electrons and one lone pair

Question 3

How many electrons does the s orbital hold?

Answer 3

The s orbital holds 2 electrons.

Question 4

How many electrons does the p orbital hold?

Answer 4

The p orbital holds 6 electrons.

Question 5

How many electrons does the d orbital hold?

Answer 5

The d orbital holds 10 electrons

Question 6

How many electrons does the f orbital hold?

Answer 6

The f orbital holds 14 electrons.

Question 7

What is the chemical formula of bleach?

Answer 7

NaClO

Question 8

Is oxidation an increase or decrease in oxidation number?

Answer 8

Oxidation is an increase in oxidation number.

Question 9

Is reduction an increase or decrease in oxidation number?

Answer 9

Reduction is a decrease in oxidation number.

Question 10

What is the reaction between CO and NO in a catalytic converter?

Answer 10

2CO + 2NO –> 2CO2 + N2

Question 11

“why would it be difficult to determine the enthalpy change of formation of hexane directly?”

Answer 11

• many different hydrocarbons would form
• activation energy too high
• reaction too slow
• they don’t react together

Question 12

What is the empirical formula of cyclohexane?

Answer 12

C6H14

Question 13

What is a reaction of chlorine radicals with ozone in which the chlorine radical is not used up?

Answer 13

Cl + O3 –> ClO + O2
ClO + O –> Cl + O2

overall: O3 + O –> 2O2

Question 14

What is a reaction of chlorine radicals with methane in which the chlorine radical is not used up?

Answer 14

Cl + CH4 –> CH3 + HCl
CH3 + Cl2 –> CH3Cl + Cl

overall: CH4 + Cl2  CH3Cl + HCl

Question 15

How do catalysts help make processes more sustainable?

Answer 15

• catalyst not used up in reaction
• reactions can take place at lower temperatures
• different reactions can be used
• less hazardous chemicals
• catalysts or enzymes can generate specific products

Question 16

What is the chemical equation for the fermentation of sugars to make ethanol?

Answer 16

C6H12O6 –> 2C2H5OH + 2CO2

Question 17

What does the diazonium ion look like?

Answer 17

(benzene ring with -N+tripleN)

Question 18

What is the atom economy?

Answer 18

Atom economy is a way to measure the atoms wasted when making a chemical. The higher the atom economy, the ‘greener’ the process. 100 per cent atom economy means that all the atoms in the reactants have been converted to the desired product.

Question 19

What is the equation for atom economy?

Answer 19

(Mr of desired product / Mr of all reactants) X 100

Question 20

What is the percentage yield?

Answer 20

The % yield of a reaction is the percentage of the product obtained compared to the theoretical maximum (predicted) yield calculated from the balanced equation.

Question 21

What is the equation for percentage yield?

Answer 21

(Actual mass / theoretical mass) x 100