Work Problem: Calculation of Molar Mass of Unknown Base Using Titration With a Strong Acid

Given Question: A student titrates 2.0135 grams of an unknown monobase weak base to the equivalence point with 67.02 mL of .5003 M HCl(aq). What is the molar mass of the weak base?  Step 1: This is to sort out what we're given in the equation, as well as some previous knowledge. We'll use the first … Continue reading Work Problem: Calculation of Molar Mass of Unknown Base Using Titration With a Strong Acid

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

Determining the Density of a Face-Centered Aluminum Cell

Crystals come in unique shapes, but all usually have an organized, repeating structure known as a lattice. For more information about metal lattices check out: https://www.seas.upenn.edu/~chem101/sschem/metallicsolids.html  Given Problem: An aluminum crystal has a face-centered unit cell. An aluminum atom has a radius of 143 picometers. What is the density of the solid crystal aluminum in g/cm³?  … Continue reading Determining the Density of a Face-Centered Aluminum Cell

Gas Volume Stoichiometry Problem

Given Problem: Methanol (CH3OH) can be synthesized as: CO+2H2→CH3OH. What volume in liters of H2(g) is needed to make 35.7 grams of CH3OH?  1. We are given the temperature at 355 K and the pressure is 738 mmHg. 2.  First, you must convert the target mass of CH3OH to moles. To do this, you use the molar mass … Continue reading Gas Volume Stoichiometry Problem

Calculating Final Temperature of Heated Al in H2O (Example)

Given Problem: A block of Aluminum has a mass of 32.5 grams and is at 45.8° C. It's placed in 105.3 grams of water at 15.4° C. What's the final temperature for both the aluminum and water? 1.  These are the equations we're going to use. Because we have two equations for q, we can substitute … Continue reading Calculating Final Temperature of Heated Al in H2O (Example)

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