Topic 1: Stoichiometry
Calculate the concentration of the solution formed when 0.5 mol of glucose is dissolved in 5.0 dm3 water.
0.1 mol dm-3
If electrons don't fill the lowest energy subshell before moving on to the next subshell, which rule is being violated?
Aufbau Principle
What does the term "Periodic" mean?
Repeating patterns
Explain why molecules that are ionically bonded have high melting points.
Due to electrostatic attraction being extremely strong, therefore requiring a lot of energy in the form of heat to break
What are the mathematical symbols in the equation: q = mCΔT?
q = heat m = mass (in grams) C = specific heat ΔT = change in temperature (in Celsius)
Mg + 2HCl --> MgCl2 + H2 What mass of hydrochloric acid (MM=36.5 g/mol) is needed to react with 2.50 moles of magnesium?
What is 182 g HCl?
This is how many electrons (e-) are in the isotope.
73Li1+
What is 2?
Charge = p+ - e-
1 = 3 - 2
What is the name of the family that will lose 2 electrons to satisfy the octet rule? What is the charge of elements after they do this?
The Alkaline Earth Metals.
Charge = +2
Draw the Lewis structure of O3 and include the resonance structures and bond order
[ O O O ] <-> [ O O O]
Bond order = 1.5
How much heat is required to raise the temperature of 250.0g of mercury by 52.0°C? (the specific heat for mercury is 0.14 J/g°C)
What is 1820J
Calculate the mass of copper (II) sulfate pentahydrate, CuSO4●5 H2O (Mr = 249.7 g mol-1) present in 25.0 cm3 of a 0.500 mol dm-3 solution.
3.12 g
The electron is in this state when it is energized by light and jumps up to a higher energy level.
What is the excited state?
Which 2 periodic families are the most reactive? WHY?
Alkali Metals and the Halogens because they are both close to having 8 valence electrons.
Explain why Magnesium has a stronger metallic bond then Calcium?
Magnesium has a smaller radius which keeps the outermost electrons closer to the positive nucleus.
P4(s) + 3O2(g) -> P4O6(s) HӨf= –1600 kJ mol–1 P4(s) + 5O2(g) -> P4O10(s) HӨf= –3000 kJ mol–1
What is the enthalpy change, in kJ mol–1, for the reaction below?
P4O6(s) + 2O2(g) -> P4O10(s)
–1400kJ mol–1
A sample of gas has a volume of 445 cm3 and a mass of 1.500 g at a pressure of 95 kPa and a temperature of 28oC. Calculate its molar mass where R = 8.314 J/mol·K
88.84 g mol-1
How many orbitals AND electrons are found in any d-subshell?
(must get BOTH)
5 orbitals, 10 electrons.
What is the product of Li2O + HOH -->
Is it an acid or a base?
LiOH
Base
Explain in terms of intermolecular forces, why water has a higher boiling point than sulfur dioxide.
Water has: London dispersion forces, permanent dipole, and hydrogen bonding.
Sulfur dioxide only has London dispersion forces and permanent dipole.
Use the enthalpy change of formation values in the table to calculate the enthalpy change for the following reaction:
4 NH3 (g) + 3 O2 (g) → 2 N2 (g) + 6 H2O (l)
ΔHfθ / kJ mol-1
NH3 (g) -46
H2O (l) -286
-1532
20.0 cm3 of sulfuric acid titrate was neutralized with 25.0 cm3 of 0.1 mol dm-3 sodium hydroxide standard solution. Calculate the concentration of the acid.
H2SO4 + 2 NaOH 🡪 Na2SO4 +2 H2O
25.0 cm3 *[1 dm3 / 1000 cm3] = 0.025 dm3 NaOH
0.025 dm3 NaOH * 0.1 mol dm-3=0.0025 mol NaOH
0.025 mol NaOH * [1 mol H2SO4 / 2 mol NaOH] = 0.00125 mol H2SO4
C = n/v = 0.00125 mol H2SO4 / 0.020 dm3
H2SO4 = 0.0625 mol dm-3 H2SO4
Magnesium has three stable isotopes, Mg-24, Mg-25 and Mg-26. The lightest isotope, Mg-24, has a percentage abundance of 78.9% %. Calculate the percentage abundance of the heaviest isotope to one decimal place.
9.9%
Write the balanced equation where P4O10 reacts with water and the product that this will form. Is the product an acid or a base?
P4O10 + 6 H2O --> 4 H3PO4
Acid
Draw the lewis structure of CHCl3 and identify if it is polar or non-polar.
Polar
Use the bond enthalpies below to calculate ∆H ⊖ for the reaction: 2H2(g) + O2(g) → 2H2O(g)
O=O, +498 KJ/mol
H-H, +436 KJ/mol
O-H, +464 KJ/mol
–486 kJ