Chemistry 5072 Avogadro’s Constant. Mass of 1 atom What is the mass of 1 proton? 1.67 X 10 -24 g o...
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Transcript of Chemistry 5072 Avogadro’s Constant. Mass of 1 atom What is the mass of 1 proton? 1.67 X 10 -24 g o...
Chemistry
5072Avogadro’s Constant
Mass of 1 atom• What is the mass of 1 proton?
1.67 X 10-24go What is the mass of 1 neutron?
1.67 X 10-24go What is the mass of one Hydrogen atom?
1.67 X 10-24gBecause hydrogen atom has only one proton
Mass of 1 atom ctd…
• What is the mass of 1 carbon atom?
12 X 1.67 X 10-24go What is the mass of 1 sodium atom?
23 X 1.67 X 10-24g
Molar mass
He S
Mg C
42
3216
2412
12 6
Let’s take the mass number as the mass in gram, how many atoms are there? (i.e. how many atoms are there in 4g of He?)
Avogadro’s constant
• Well, you know that given the mass number in grams, there are 6 X 1023 atoms/particles.
• 6 X 1023 is a constant number and this is termed as Avogadro’s constant.
• 4g of He, 32g of S, 24g of Mg and 12g of C contain 6 X 1023 particles. The mass which gives 6 X 1023 particles is termed as Molar mass!
Mole• One mole of any substance contains 6 X 1023 of particles.
• Therefore, molar mass of Na is 23g/mol.
• How about molar mass of:a)Znb)Sic)Ard)Ca
Analogy
Mass of 1 orange = mass of 1 apple = 10g
If the basket can contains 2 apples and 2 oranges, what is the mass of the basket now?
Mass of basket = 0g
40g
If one container can take in 10 baskets, what is the mass of the container? 400g
Analogy ctd…
Mass of 1 orange = mass of 1 apple = 10g
If the basket can contains 5 apples and 5 oranges, what is the mass of the basket now?
Mass of basket = 0g
100g
If one container can take in 10 baskets, what is the mass of the container?
1000g
Analogy
Mass of 1 orange = mass of 1 apple = 10g
If the basket can contains 2 apples and 2 oranges, what is the mass of the basket now?
Mass of basket = 0g
40g
If 1 container can take in 10 baskets, what is the mass of the container?
400g
proton neutron
nucleus
Mass number
Molarmass
Avogadro’s constantmole
Mole• 1 mole of any substance contains 6 X 1023 particles.
• How many particles are there in 2 moles of Na?1.2 X 1024 particles of Na
o How many particles are there in 3 moles of C?1.8 X 1024 particles of C
o How many particles are there in 0.25 of Ti?1.5 X 1023 particles of Ti
Mole ctd…• If there are 4 X 1023 particles of Mg, how many moles of Mg are there?4 X 1023 particles = 0.667 moles (3 sf)6 X 1023 particles
• If there are 1.5 X 1022 particles of He, how many moles of He are there?1.5 X 1022 particles = 0.0250 moles (3 sf) 6 X 1023 particles
Mole
Number of particles
X (6X1023) ÷ (6X1023)