Organic Chem- Alkanes Flashcards
1
Q
What are alkanes??
A
Hydrocarbon based molecules with no double bonded. They are Saturated
2
Q
How do you work out empirical formula from % composition??
A
- Divide the % by the Mr of each element to get a molar ratio
- Turn into smallest whole number ratio
- divide both by smallest number
- turn into whole number ratios
- divide the Mr of what you’ve worked out by the Mr given in the Q and multiple your molecule by that number
3
Q
Why does boiling point of hydrocarbons increase as chai length increasing
A
London forced between molecules increase because there are more electrons to create stronger temporary dipoles—
4
Q
Why do more branched molecules have lower boiling points than unbranched molecules??
A
They are less tightly packed together and have less surface contact so the straight chains have stronger wan Der Waals forces
5
Q
Why are branched molecules better as fuels
A
more efficient combustion
