Exit Ticket 16

How many atoms are there in a 2 moles of oxygen atoms? How many atoms are there in 2 moles of oxygen molecules?

12 x 10^23 and 24 x 10^23

How many grams of carbon are in 12 x 10^23 atoms of carbon?

24

If there are 12 x 10^23 oxygens in a sample of water, how many grams of hydrogen are in the sample?

4 grams

What percentage of the mass of hydrofluoric acid (HF) is contributed by hydrogen?

5%

How many grams of oxygen are in a sample of carbon dioxide (CO2) that has 24 grams of C?

64 grams

Joules

Energy

J

J=energy=kg m2/s2

What mathematical tool do we use to determine the ratio of elements in a compound?

Stoichiometry

Diatomic elements are important. What makes them different from other elemental substances?

The atoms are found in pairs in nature

Why is it possible to do compositional stoichiometry problems in your head?

The value for Avogadro's number is rounded off to 6 x 1023 The number of atoms in a molecule are simple integers The mass of atoms can usually be rounded to simple integer numbers

k

kilograms (mass)

m

meters (units)

s

seconds (time)