The mole & the Avogadro constant

Question 1

What is the formula for moles?

Answer 1

n=m(g)/mr

Question 2

What is concentration?

Answer 2

The measure of the amount of substance per unit of volume.

Question 3

What is the formula for concentration?

Answer 3

conc=moles/volume(dm^3)

Question 4

How do you convert from cm^3 to dm^3

Answer 4

÷ 1000

Question 5

How do you convert from mm^3 to to dm^3?

Answer 5

÷ 1000000 or 10^-6

Question 6

What are all the common reactions in chemistry?

Answer 6

• substance + oxygen -> oxides
• metal + water -> metal hydroxide + hydrogen
• metal + acid -> salt + hydrogen
• oxide + acid -> salt + water
• hydroxide + acid -> salt + water
• carbonate + acid -> salt + water + carbon dioxide
• hydrogencarbonate + acid -> salt + water + carbon dioxide
• ammonia + acid -> ammonium salt
• metal carbonate + acid -> metal oxide + carbon dioxide (heating)
• hydrocarbon + oxygen -> water + carbon dioxide (combustion)
• metal hydroxide (heat) -> metal oxide + water(g)
• A + BC -> AC + B (single displacement reaction) (apart from halogens where they displace each other)
• AB + CD -> AD + CB (double displacement reaction)
• aq + aq -> solid ( precipitate reaction) (if no solid then so reaction has taken place)

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Question 7

What are the common ions in chemistry?

Answer 7

hydroxide OH-
nitrate NO3 -
sulfate SO4 2-
carbonate CO3 2-
hydrogen H+
ammonium NH4 + (ammonia is NH3)

Question 8

What is the mole?

Answer 8

Unit used to measure amount of substance

Question 9

What is avogadros constant

Answer 9

The number of particles in one mole of a substance (6.022 x 10^23)

Question 10

What is the formula for working out the number of particles?

Answer 10

No. of particles = No. of moles x avogadro’s constant