Biology Calculation

Answer 1

There are two ways you can calculate the solution:

1. 100 µg/ml = 0.1 mg/ml

2.0 mg/ml is 20 times the required concentration. If you dilute 15 ml twenty times, it will yield 300 ml, which is less than the amount you need.

2.

Needed solution: 500 ml x 0.1 mg/ml = 50 mg of ethidium bromide

Have on hand: 15 ml x 2.0 mg/ml = 30 g ethidium bromide, again, less than the required amount.

Answer 2

Hello Sarah,

In order to determine to determine if you have enough, you first need to know how much you have and how much you need.

To determine how much you have in terms of Micrograms (15ml of a 2.0mg/ml solution), you will need to convert the 2mg/ml into micrograms. There are 1000 micrograms in one gram, so our solution is 2000 micrograms/ml. We have 15 ml, so we have a total of 30,000 micrograms of ethidium bromide.

To determine how much we need, we need 500ml of the 100micrograms/ml, for a total of 50,000 micrograms of ethidium bromide needed.

There is not enough.

Answer 3

So EtBr: ~394g/mol

How many grams / moles of EtBr (Ethidium Bromide) do we have?

We .015L of a 2g/L ( mg/mL ==equivalent to g/L)...

so that means we have .03 grams of EtBr dissolved in the fridge.

30mg we have.

What do we need?

.500L of 100mg/L is what we need Why? ((ug/mL == mg/L),

This solution would require

0.500L * 100mg/L = 50mg of EtBr (0.050g).

So ---we don't have enough to make 500 mils at this concentration.

We could however make 300mils---we would have to add solvent to our stock.