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Calculating Product with a Limiting Reactant
Calculating Heat of Reaction
Naming Polyatomic Ions
DrawingLewis Structures (Polarity, Angles, Geometry, and Shape)
Other
100

Nitrogen gas reacts with hydrogen gas to form ammonia:

N2+3H2→2NH3

If you start with 2.0 mol N2 and 3.0 mol H2, which reactant is limiting?

Hydrogen (H₂) is the limiting reactant.

100

If a reaction absorbs heat from the surroundings, is it endothermic or exothermic?

Endothermic

Endothermic = heat goes IN to the system from the surroundings.

100

Name the compound: NaNO₃

Sodium Nitrate 

100

Draw the Lewis structure of CO₂. What is its molecular shape, electron geometry, and is it polar or nonpolar?

  • Lewis structure:
    O = C = O (each O has 2 lone pairs)

  • Shape: Linear

  • Geometry: Linear 

  • Bond angle: 180°

  • Polarity: Nonpolar

100

Which atom has the larger atomic radius:
Na or Cl?

Na

200

If 3.0 mol H2 is limiting, how many moles of ammonia (NH₃) will form?

 3H2→2NH3


2.0 mol NH3

200

In an exothermic reaction, does the temperature of the surroundings increase or decrease?


Increase 

Exothermic reactions release heat, warming up the surroundings.

200

Name the compound: KNO₂


Potassium Nitrite 

200

Draw the Lewis structure of NH₃. What is its molecular shape and polarity?


  • Shape: Trigonal pyramidal

  • Geometry: Tetrahedral

  • Bond angle: ~109°

  • Polarity: Polar

200

A gas occupies 2.50 L at 1.00 atm. If pressure increases to 2.50 atm at constant temperature, what is the new volume?

(hint: Boyle's Law)

V2=1.00 L

(1.00)(2.50)=(2.50)(V2)⇒V2=1.00 L

300

Magnesium reacts with oxygen:

2Mg+O2→2MgO

You have 12.2 g Mg and 10.0 g O₂.
How many grams of MgO can be produced?

Mg: 0.50 mol

O: 0.3125 mol

For 0.50 mol Mg, we require 0.25 mol O₂ → we have 0.3125 mol of O, so Mg is limiting. 

Answer: 20.2 g MgO

300

A cold pack used for injuries becomes colder when activated. What type of reaction is happening?


Endothermic

It absorbs heat from your skin, causing the cooling effect.

300

Name the compound: FeSO₄

Iron(II) sulfate

300

Draw the Lewis structure for SO₂ and determine polarity, shape, geometry, and bond angles.

  • Shape: Bent

  • Geometry: Trigonal Planar

  • Bond angle: 120°

  • Polarity: Polar

300

The combustion of propane has ΔH=−2220 kJ/mol 


Is this reaction exothermic or endothermic, and does the temperature of the surroundings increase or decrease?


  • Exothermic

  • The temperature of the surroundings increases


400

Aluminum reacts with chlorine:

2Al+3Cl2→2AlCl3

You start with 5.0 g Al and 15.0 g Cl₂.
Calculate:
a) Limiting reactant
b) Mass of AlCl₃ produced
c) Mass of excess reactant remaining

a) Cl₂ is limiting
b) 18.8 g AlCl₃
c) 1.19 g Al leftover

400

When methane gas burns in oxygen and produces a flame, is this an exothermic or endothermic reaction?


Exothermic

Combustion always releases heat and light energy.

400

Name the compound: (NH₄)₂CO₃

Ammonium carbonate

400

Draw the Lewis structure for CH₄. Give the electron geometry, molecular shape, and polarity.


  • Electron geometry: Tetrahedral

  • Molecular shape: Tetrahedral

  • Bond angle: 109°

  • Polarity: Nonpolar

400

Write the complete electron configuration of Calcium. 


1s22s22p63s23p64s2 
500

Iron(III) oxide reacts with carbon monoxide:

Fe2O3+3CO→2Fe+3CO2

Given 25.0 g Fe₂O₃ and 15.0 g CO:
How many grams of iron (Fe) form?

17.5 g Fe

500

During an endothermic reaction, what happens to the enthalpy (ΔH) value: positive or negative?

Positive 

Energy is absorbed, so the system’s heat content increases → ΔH>0

500

Name the Compound: Mg(ClO₄)₂

Magnesium perchlorate

500

Draw the Lewis structure for PCl₃. Identify the molecular geometry, shape, bond angle, and polarity.


  • Molecular Geometry:
    Tetrahedral

  • Shape: Trigonal Pyramidal

  • Bond Angle:
    ~109°

  • Polarity:
    Polar

500

Which molecule is more polar: HF or HCl?


HF