# Tutor profile: Neal R.

## Questions

### Subject: Chemistry

You are performing a titration in the lab. You have a 25.00 mL sample of an unknown acid of unknown concentration that you know is monoprotic. You are titrating the acid with 0.500 M NaOH. When you finish the titration, your equivalence point was determined to be 13.55 mL of NaOH. What is the concentration of the unknown acid?

The first piece of information we need for this solution comes from the unknown acid being monoprotic. This means that we know that there is only one H+ from each molecule/formula unit of acid. Since we are titrating it with NaOH, we know that the molar equivalents between acid and base is 1:1. The next step is to calculate the amount of moles of NaOH we used to titrate the acid. To do this, we multiply our volume of NaOH in liters by our concentration of NaOH: (0.01355 L * 0.500 M) = 0.00678 moles of NaOH used. Now that we know the moles of base, we know from the ratio we calculated earlier that the acid will have the same number of moles. We know that Molarity is the same as moles per liter, so we can divide the number of moles by the volume of acid we started with: (0.00678 moles / 0.02500 L) = 0.271 M Unknown Acid

### Subject: Basic Chemistry

Explain what a covalent bond is.

A covalent bond is a bond between two atoms that are nonmetals. In a covalent bond, electrons are 'shared' between the two atoms. When atoms share these electrons, it allows them to fill their valence shell without becoming charged. The two atoms are also then attracted to each other by sharing these electrons, so they are bonded to each other through this.

### Subject: Algebra

Tom works on a pumpkin and potato farm. He can sell each pumpkin for $5 and each potato for $1. He is able to pick and sell 5 pumpkins and 25 potatoes per day. If Tom wants to save up $200 to buy hay bales, how many days must he work to be able to buy it?

First, we must solve for how much money Tom is able to make in one day. To do this, we have to multiply the number of pumpkins by the amount of money. This give us $25 for the pumpkins per day. Then, we must multiply the number of potatoes by the amount of money he makes. This gives us $25 for the potatoes per day. We now have to add these up to give us $50 per day that Tom works. This can be shown by the expression: $50x where x is the number of days worked. We can set the expression equal to the amount of money Tom needs to save, which is $200. This gives us the equation $50x = $200. We can now divide 200 by 50, which gives us a value of x = 4. This means that tom must work 4 days to get his hay bales.