# Question #24972

##### 1 Answer

The molarity of the **1X** **Running Buffer** will be **0.0035 M**.

Start by looking at the **10X** solution. You know that this buffer must have a **1% w/v** percent concentration of sodium dodecyl sulfate (SDS), and that you have **1-L** of solution.

A **1% w/v** solution will contain **1 g** of SDS in **100 mL** of solution, which means that, in order to keep the percent concentration by mass unchanged, a larger volume will require more SDS present.

To determine the molarity of the **10X** solution, use the molar mass given to calculate how many moles of SDS are present

Since you have **1 L** of solution, you'll get

Because the concentration of a **10X** solution is *10 times higher* than the concentration of the **1X** solution, the molarity of the **1X** solution will be

In other words, the **1X** solution is obtained by diluting the **10X** solution *ten-fold*.

I will leave the answer rounded to two sig figs, although your data indicates that it should be rounded to one sig fig