# The pH of concentrate

### introduction

I set this up and critiqued it in this blog before teaching it. The basic idea is that I needed a way into logarithms with my College Algebra students.

### The questions

I have two question videos. I debated which to use in class and ultimately chose the first option below.

#### Option Number 1

In this option, we measure the pH of water and the pH of pure orange juice concentrate.

#### Option Number 2

In this option, we measure the pH of water and the pH of 100 ml of water mixed with 1 ml of orange juice concentrate.

I imagine that Option 1 will prompt questions such as, “What is the pH of regular orange juice?” and “What if we mix it 50-50?”

I imagine that Option 2 will also prompt the question, “What is the pH of the straight-up concentrate?”

In fact, this last question is the one that motivated this project. I was expecting (as will my students) that the difference between the pH of juice and the pH of concentrate will be quite large.

#### Juice (20 ml)

This actually doesn’t demonstrate juice (see post where I regret this oversight in my data collection). But it’s pretty close. Real OJ should be 3:1 water to concentrate. This is 5:1.