Unit Conversions © R. A. Hill

Unit Conversions Within the S.I. System Need to know prefixes used in S.I. system

S.I. Prefixes: pp 10 in text Prefix Multiple Symbol mega kilo hecto deka deci centi milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo hecto deka deci centi milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto deka deci centi milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka deci centi milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci centi milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi 10-2 c milli micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Ex: 1 Mm = ___m

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Ex: 1 Mm = 106 m  

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Ex: 1 Mm = 106 m 1 ns = ____s  

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Ex: 1 Mm = 106 m 1 ns = 10-9 s  

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Ex: 1 Mm = 106 m 1 ns = 10-9 s   1 mmol = ___mol

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Ex: 1 Mm = 106 m 1 ns = 10-9 s   1 mmol = 10-3 mol

S.I. Prefixes: Prefix Multiple Symbol mega 106 M kilo 103 k hecto 102 h deka 10 da deci 10-1 d centi 10-2 c milli 10-3 m micro 10-6 μ nano 10-9 n pico 10-12 p Memorize these 6 prefixes.

S.F. in Nonmeasured Numbers   If a number is not measured then it does not have an estimated digit in it.  treat it as if it has ∞ S.F. Ex: #s in definitions 12 objects = 1 dozen objects 1 mm = 10−3 m counting number of objects i.e. 15 people

S.D. in Conversion Factors   Conversion factors involving the def. of prefixes have ∞ S.F. Ex: In 1 km = 103 m, both the 1 and the 103 have ∞ S.F. When both #s in a relationship have ∞ S.F. it is called an exact relationship. Conversion factors not involving the def. of a prefix or def. have a limited # of S.F. Ex: In 2.2 lbs = 1 kg, the 2.2 has 2 S.F. & the 1 has ∞ S.F.

Unit Conversions Within the S.I. System 243 mm = ? m

Unit Conversions Within the S.I. System 0.01 km = ? cm

Unit Conversions Between Different Systems of Measurement 3.21 cal = ? J

Unit Conversions Between Different Systems of Measurement 8.9 lbs = ? g

Unit Conversions Between Different Systems of Measurement 0.20 km = ? in

Squared and Cubed Conversion Factors 562 in2 = ? ft2 Wait… 1 ft = 12 in but does 1 ft2 = 12 in2 ? 1 ft2 562 in2 = 12 in2

Well, this is 1 ft2… 1 ft 1 ft

And this is 1 ft2… 12 in 12 in

which is 144 in2 ! 12 in 12 in

562 in2 = ? ft2 2 1 ft 562 in2 = 3.9027… ft2 = 3.90 ft2 12 in Squaring the entire conversion factor gives the relationship between squared units! Lets try this again…

Cubing the entire conversion factor gives the relationship between cubed units! So for ft3 and in3 … 0.74 ft3 = ? in3 3 12 in 0.74 ft3 = 12 in 1 ft = 1278.72 in3 = 1300 in3 12 in 12 in

Unit Conversions Between Different Systems of Measurement 3.25 g/ml = ? lbs/ft3

Unit Conversions with Equivalent Measurements density (def) – the mass per volume for a substance. What is the mass of 1.25 l of Hg (density = 13.6 g/ml)?

atomic weights (def)

atomic weights (def) – the average mass of an atom of an element relative to an atom of carbon-12 being assigned a mass of exactly 12 a.m.u.

atomic weights (def) – the average mass of an atom of an element relative to an atom of carbon-12 being assigned a mass of exactly 12 a.m.u.

atomic weights (def) – the average mass of an atom of an element relative to an atom of carbon-12 being assigned a mass of exactly 12 a.m.u. a.m.u. = atomic mass unit  

atomic weights (def) – the average mass of an atom of an element relative to an atom of carbon-12 being assigned a mass of exactly 12 a.m.u. a.m.u. = atomic mass unit   These can be found on the periodic chart. Ex: hydrogen

atomic weights (def) – the average mass of an atom of an element relative to an atom of carbon-12 being assigned a mass of exactly 12 a.m.u. a.m.u. = atomic mass unit   These can be found on the periodic chart. Ex: hydrogen 1.008

formula weight

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.  

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H 1 O

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H (1.008) 1 O

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H 2(1.008) 1 O

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H 2(1.008) 1 O (16.0)

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H 2(1.008) 1 O 1(16.0)

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H 2(1.008) = 2.016 1 O 1(16.0) = 16.0 18.016

formula weight (def) – the sum of all the atomic weights of every atom present in the formula for a substance.   Ex: H2O 2 H 2(1.008) = 2.016 1 O 1(16.0) = 16.0 18.016 = 18.0 = f.w.

mole (def)

mole (def) – a quantity of substance that contains as many particles as there are atoms present in exactly 12 g of carbon-12.  

mole (def) – a quantity of substance that contains as many particles as there are atoms present in exactly 12 g of carbon-12.   This # has been experimentally determined to be:

mole (def) – a quantity of substance that contains as many particles as there are atoms present in exactly 12 g of carbon-12.   This # has been experimentally determined to be: 6.022 x 1023

mole (def) – a quantity of substance that contains as many particles as there are atoms present in exactly 12 g of carbon-12.   This # has been experimentally determined to be: 6.022 x 1023 Avogadro’s Number

mole (def) – a quantity of substance that contains as many particles as there are atoms present in exactly 12 g of carbon-12.   This # has been experimentally determined to be: 6.022 x 1023 Avogadro’s Number In problems, the word “particles” is replaced with the term “atom”, “molecule” or whatever is appropriate.

molar mass

molar mass (def) – the mass of 1 mole of a subs.  

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol.

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol. Ex: C

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol. Ex: C 12.0

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol. Ex: C 12.0 g/mol

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol. Ex: C 12.0 g/mol H2O

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol. Ex: C 12.0 g/mol H2O 18.0

molar mass (def) – the mass of 1 mole of a subs.   This is numerically equal to the formula weight of the subs. but has units of g/mol. Ex: C 12.0 g/mol H2O 18.0 g/mol

molar volume

molar volume (def) – the volume of 1 mole of a subs.  

molar volume (def) – the volume of 1 mole of a subs.   The molar volume of any gas at S.T.P. is

molar volume (def) – the volume of 1 mole of a subs.   The molar volume of any gas at S.T.P. is S.T.P. = standard temperature & pressure =

molar volume (def) – the volume of 1 mole of a subs.   The molar volume of any gas at S.T.P. is S.T.P. = standard temperature & pressure = OoC & 1 atm

molar volume (def) – the volume of 1 mole of a subs.   The molar volume of any gas at S.T.P. is 22.4 l/mol. S.T.P. = standard temperature & pressure = OoC & 1 atm

particles mol g L Avogadro’s molar mass number molar volume 6.022 x 1023 particles mol 1 mol g x x 1 particles mol g Avogadro’s number molar mass 1 mol particles g mol x x 1 6.022 x 1023 molar volume 22.4 L mol mol L 1 x x 22.4 1 L Gas at S.T.P.

particles mol g L Avogadro’s molar mass number molar volume 6.022 x 1023 particles mol 1 mol g x x 1 particles mol g Avogadro’s number molar mass 1 mol particles g mol x x 1 6.022 x 1023 molar volume 22.4 L mol mol L 1 x x 22.4 1 L Gas at S.T.P.

0.25 mol H2O contains how many H atoms?

What is the mass of 24.7 mmol of Fe2(SO4)3?

0.458 mol of CH4 gas occupies how many ml at S.T.P.?

A 1 carat diamond (pure C) has a mass of 0. 200 g A 1 carat diamond (pure C) has a mass of 0.200 g. How many C atoms are present in a 1 carat diamond?

Octane (C8H18) has a density of 0. 80 g/ml Octane (C8H18) has a density of 0.80 g/ml. What is the volume in ml of 1.00 x 1024 molecules of C8H18?

soln solution (def) – a homogeneous mixture. solute (def) – the substance present in a solution in the lesser amount. solvent (def) – the substance present in a solution in the greater amount.

molarity (def) – the number of mole of solute per liter of solution. The units of mol/l soln are abbreviated as “M” & read as “molar”.

Ex: volumetric flask Add H2O until V of soln = 1 liter 1 liter mark 3 mol of NaCl 1 l NaCl soln 3 mol NaCl 3 M NaCl soln Note: (1) less than 1 liter of solvent is added & the amount will differ with each solute (2) in making solns, volumes are not always additive   ex: 50 ml H2O + 50 ml C3H7OH = 96 ml soln …V of H2O + V of C3H7OH > V of soln V of NH4Cl + V of H2O < V of soln

How would 1.000 l of 2.00 M CaCl2 be prepared?

1.52 g of NaOH is diluted with H2O until a solution with a total volume of 250.0 ml is obtained. What is the molarity of the NaOH solution?

Solution Dilution Stock Solns Concentration H2SO4 18 M HNO3 16 M HCl 12 M HC2H3O2 17 M NH4OH 15 M

 V • M = n add more solvent solvent solute n1 = n2 mol L x = mol L V1 • M1 = V2 • M2

How would 100.0 ml of 1 M HNO3 be prepared?