Limiting Reactants
Thermochemistry & Enthalpy
Hess Law
Waves & Light
Quantum Numbers & Orbitals
100

This term describes the reactant that is completely used up first in a chemical reaction, stopping the reaction from making more product.

What is limiting Reactant?

100

When heat is released by the system into the surroundings, the process is known by this term. 

What is exothermic? 

100

According to the properties of enthalpy, if you reverse the direction of a chemical reaction, what happens to the sign of its ΔH?  

What is it changes to the opposite sign (ΔHforward = –ΔHreverse)?
 

100

According to the wave equation, if the wavelength of electromagnetic radiation increases, what happens to its frequency?

What is it decreases?

100

True or False: As 'n' becomes larger, the atom becomes larger and the electron is further from the nucleus.

What is true?

200

0Consider the reaction

N2+3H2→2NH3

You start with 3.0 moles of N₂ and 4.0 moles of H₂.

Which reactant is limiting?

What is H2?

200

A gas sample absorbs 145 J of heat from its surroundings while expanding and doing 85 J of work on its surroundings.

Calculate the change in internal energy (delta E) of the system in Joules.


What is +60J?

200

Use the following equations to determine ΔH for:

CO(g)+1/2 O2(g)→CO2(g)

Given:

  1. C(s)+O2(g)→CO2(g)ΔH=−393.5 kJ

  2. C(s)+1/2 O2(g)→CO(g)ΔH=−110.5 kJ

What is ΔH=−283.0 kJ?

200

Arrange the following types of electromagnetic radiation in order of increasing wavelength: Red light, X-rays, Microwaves, Ultraviolet.

What is X-rays < Ultraviolet < Red light < Microwaves?

200

What are the allowed values of the angular momentum quantum number (l) for an electron in the n = 3 energy level, and what subshell shapes do they correspond to

What are l = 0, 1, 2 (corresponding to s, p, and d orbitals)?

300

An experiment yields an actual recovery of 4.25 g of product, while the calculated theoretical yield is 5.00 g. What is the percent yield?


What is 85.0%?

300

How much heat (in Joules) is required to warm a 150.0g block of iron from 20.0°C to 75.0°C? (The specific heat capacity of iron is 0.45J/g-k).

What is 3.7 x 10^3 J (or 3712.5J)? 

300

Find ΔH for the reaction:

2NO(g)+O2(g)→2NO2(g)

Given:

  1. N2(g)+O2(g)→2NO(g)ΔH=+180.6 kJ

  2. N2(g)+2O2(g)→2NO2(g)ΔH=+66.4 kJ

What is ΔH=−114.2 kJ?  

300

What is the energy of a single photon that has a frequency of 7.25 x 10^14 (s-1)  

What is 4.80 x 10^-19J?

300

What is the total number of individual orbitals present in the n = 3 energy level?

What is 9 orbitals?

400

Determine the theoretical yield of NH₃ (in grams) if 25.0 mol Ca₃N₂ and 60.0 mol H₂O are reacted according to the following balanced reaction. A possibly useful molar mass is NH₃ = 17.031g/mol .

Ca3N2(s)+6H2O(l)→3Ca(OH)2(s)+2NH3(g)


What is 340.62 g NH3?

400

Calculate the heat (in Joules) needed to warm 250g of water from an initial temperature of 22°C to a final temperature of 98°C

What is 7.9 x 10^4 J (or 79,496 J)?

400

Determine ΔH for: 

N2 (g) + 2O2 (g) → 2NO2 (g)

Given:

1. N2(g) + O2(g) → 2NO(g) ΔH = +180.6KJ

2. NO(g) + 1/2 O2(g) → NO2(g) ΔH = -57.1KJ


What is ΔH=+66.4 kJ?  

400

Calculate the energy of a single photon of blue light with a wavelength of 450nm

What is 4.42 x 10^-19J?

400

What are the exact values of n and l, and all allowed values of ml, for an electron occupying a 3p orbital

What is n = 3, l = 1, and ml = -1, 0, +1?

500

Consider the reaction: CaCO3 + 2HCl → H2O + CO2. 

If 10.0g of CaCO3 (MM = 100.09g/mol) and 10.0g of HCl (36.46g/mol) are combined, which reactant limits the production of CO2

 

What is Calcium Carbonate (CaCO3)?

500

When 4.00g of methylhydrazine (CH6N2, MM=46.1g/mol) is combusted in a bomb calorimeter, the temperature increases from 25.00°C to 39.50°C . If the heat capacity of the calorimeter is 7.794 KJ/°C, calculate the heat of reaction per mole CH6N2.

What is -1.30 x 10^3 KJ/mol (or -1302kJ/mol)?

500

Using the standard enthalpies of formation:

  • ΔH°f (CO₂(g)) = −393.5 kJ/mol
  • ΔH°f (H₂O(l)) = −285.8 kJ/mol
  • ΔH°f (C₂H₆(g)) = −84.7 kJ/mol
  • ΔH°f (O₂(g)) = 0 kJ/mol

Calculate ΔH° for the combustion of ethane:



What is −1559.7 kJ?

500

Calculate the energy change (𝛥E, in Joules) when an electron in a hydrogen atom transitions from the n = 4 energy level to the n = 2 energy level. 

Is light absorbed or emitted?

What is -4.09 x 10^-19J and emitted?

500

According to Hund's Rule, how many unpaired electrons are found in the 2p subshell of a neutral nitrogen (N) atom?

What is 3 unpaired electrons? 

M
e
n
u