# Charles’s Law: History and Work Problem

And we're back for the second installment of our gas laws series - Charles' Law. If you need to refresh on the other gas laws in this series you can check out our post on Boyles' Law, Avogadros' Law, and the Ideal Gas Law. Let's review what a gas is: a gas a is a … Continue reading Charles’s Law: History and Work Problem

# Determining the Molar Solubility of Iron (II) Hydroxide

Given Question: Calculate the molar solubility of Fe(OH)2 (Ksp=4.87*10^-7).  Tutor's Note: The Ksp radical that's written down comes in later, I got confuzzled by my own notes! Happens to all of us. Sorry students 🙂  Step 1: Write out the reaction equation with all ions. Make sure it's balanced! We'll use this in the next step with … Continue reading Determining the Molar Solubility of Iron (II) Hydroxide

# Determining Precipitate Yield (g) in Aqueous Solution

Given Question: Given the reaction: K3(PO4)+ Ni(SO4)→ K3(SO4)(aq)+Ni(PO4)(s), with 100.0 ml of K3PO4 and 200.0 ml of NiSO4 under standard conditions, how many grams of precipitate form?  Step 1: Determine the limiting reactant and the precipitate.  In order to determine the limiting reactant, one must convert all reactants to moles (mol). In this case, we can … Continue reading Determining Precipitate Yield (g) in Aqueous Solution

# Calculating the pH of a Buffer System

The point of this problem is to correctly calculate the pH of a buffer system using formonitrile, or hydrogen cyanide. Here, we use the dissociation constant and the Henderson-Hasselbach equation. Given Problem: Calculate the pH of a buffer that's .250 M HCN (kª= 4.9*10^-10) and 0.170 M KCN.  2. This is to remind us of the … Continue reading Calculating the pH of a Buffer System

# Titration of Strong Acid With Strong Base

The goal of this example is to help students become fluent in calculating pH/pOH of a solution during a titration of a strong acid (HCl) and a strong base (NaOH). This problem includes calculations for titrations of increasing volumes. Given Problem: Calculate the pH of a titration of 25.0 mL of HCl (.100 M) with … Continue reading Titration of Strong Acid With Strong Base

# Calculating Acid:Buffer Ratio using H-H Equation

Given Question: Which acid would you combine with its Na (sodium) sat to create a buffer with a pH of 7.35. What ratio of a buffer to acid is needed? There are 3 potential buffers provided to choose from. 1. First, we choose which buffer is the best acid to choose to obtain the desired … Continue reading Calculating Acid:Buffer Ratio using H-H Equation

# VSEPR Theory Examples (chem.purdue)

Given Problem: Draw the Lewis dot structures, identify the molecular geometry, and give the bond angle for the following compounds: BeF2 BCl3 SI6 1. BeF2: The first step is to draw the Lewis dot structure. This can be done by identifying how many bonding groups are involved.  A bonding group, counts as 1 lone electron, an electron pair, … Continue reading VSEPR Theory Examples (chem.purdue)

# Calculating Temperature Change Using Q=mCsΔT

This problem is designed to get you comfortable working with the equation given, and is good because it gets you to think of Q in terms of joules. Given Problem: 25 grams of gold (Au) is initially at 27°C. It absorbs 2.35 kJ of heat. What is the final temperature of the gold? The specific heat … Continue reading Calculating Temperature Change Using Q=mCsΔT

# Finding Wavelength of Light (nm) Using Frequency (Hz)

The point of this problem is to be able to use the c=λν to find the wavelength of light. This problem could also be structured to find the frequency of the light using just the wavelength. 1. The equation we're working with has two values already entered in it. The speed of light (3.00*10^8 m/s) … Continue reading Finding Wavelength of Light (nm) Using Frequency (Hz)