The Basics Reminders about simple terms and concepts. Zumdahl Chapter 3

Equations Zn + H + + Cl > Zn Cl - + H 2

Equations Zn + 2H + + Cl > Zn Cl - + H 2

Equations Zn + 2H + + 2Cl > Zn Cl - + H 2

Equations Zn + 2H + + 2Cl > Zn Cl - + H 2 Zn + 2(HCl) ----> Zn Cl - + H 2

Equations Zn + 2H + + 2Cl > Zn Cl - + H 2 Zn + 2(HCl) ----> Zn Cl - + H 2 Zn + 2H > Zn H 2

Equations Zn + 2H + + 2Cl > Zn Cl - + H 2 Zn + 2(HCl) ----> Zn Cl - + H 2 Zn + 2H > Zn H 2 Zn (s) + 2H + (aq) ----> Zn 2 + (aq) + H 2(gas)

Equations Zn (s ) + 2H + (aq) ----> Zn 2 + (aq) + H 2(gas) - means that on an atomic ratio, 1 Zn atom reacts with 2 H + ions to produce 1 Zn 2+ ion and 1 hydrogen diatomic molecule. - we don’t work on an atomic scale very often so we define a new unit which is a bunch of atoms or molecules. - we don’t count atoms very often so we work in the mass of that bunch.

Moles and Molar Masses The ‘bunch’ I alluded to earlier is the number of atoms contained in exactly kg of carbon which contains only the 12 C isotope. ( 6 protons + 6 neutrons in the nucleus.) We call this unit the MOLE. 1 mole is x particles Avogado Number.

Moles and Molar Masses Thus the MOLAR MASS is just the mass of a mole of any particular substance. May also be referred to as the atomic or molecular weight. H = g / mol = kg / mol CO 2 = g / mol = kg /mol Conceptually, this allows us to compare and calculate relative amounts of material.

Stochiometry Zn + 2(HCl) ----> Zn Cl - + H 2 one mole of zinc metal reacts with two mole of hydrogen chloride to produce one mole of zinc ions two moles of chloride ions and one mole of hydrogen gas g Zn g HCl ----> g Zn g of Cl g of H 2

IDEAL GASES Zumdahl, Chapter 5

Basic Definitions Amount in moles ( mol ) Pressure in Pascals ( N m -2 ) Volume in metre 3 ( m 3 ) Temperature in Kelvin ( K )

Pressure Pressure = force / area = Newtons / metre 2 = Pascals.

Pressure Pressure = force / area = Newtons / metre 2 = Pascals Standard atmospheric pressure = Pascals

Pressure Pressure = force / area = Newtons / metre 2 = Pascals Standard atmospheric pressure = Pascals This is equivalent to atm or a pressure that will support a column of mercury 760 mm tall in a barometer.

Volume Measured in metre 3 which may not be convenient. More common to use litres but : 1 L = m 3

Temperature We need an absolute temperature scale. i.e. one for which zero means something. We use the Kelvin scale on which ice melts at K or 0K is o C.

Boyle’s Law volume is proportional to 1 / pressure P 1 V 1 = P 2 V 2 For a fixed amount of gas at constant temperature.

Charles’ Law Volume is proportional to absolute temperature V 1 / V 2 = T 1 / T 2 For a fixed amount of gas at constant pressure.

V T o C He N2N2

Equation of state PV = n RT R = Nm mol -1 K -1 = J mol -1 K -1 For an ideal gas.

Equation of state PV = n RT If you know any three of P, V, n, and T, you can calculate the fourth. What is the volume occupied by 2.30 moles of helium at 313 K and 217 kPa?

What is the volume occupied by 2.30 moles of helium at 313 K and 217 kPa? V = n R T / P V = 2.30 mol x 8.31 Nm mol -1 K -1 x 313 K / 217 x 10 3 Nm -2 V = m 3

What is the volume occupied by 2.30 moles of helium at 313 K and 217 kPa? V = n R T / P V = 2.30 mol x 8.31 Nm mol -1 K -1 x 313 K / 217 x 10 3 Nm -2 V = m 3 DOES THIS MAKE SENSE??????????