# The osmotic pressure of blood is 7.7 atm at 25°C. What concentration of glucose, #C_6H_12O_6#, is isotonic (same osmotic pressure) with blood?

##### 1 Answer

#### Explanation:

The problem wants you to determine what concentration of glucose would produce a solution that has the same **osmotic pressure** as blood at

As you know, **osmotic pressure** is defined as the pressure *required* to prevent the flow of water across a semi-permeable membrane from a region of **lower solute concentration** into a region of **higher solute concentration** **osmosis**.

Osmotic pressure can be calculated using the formula

#color(blue)(|bar(ul(color(white)(a/a)Pi = i * c_"solute" * RTcolor(white)(a/a)|)))" "# , where

*van't Hoff factor*, equal to **non-electrolytes**

**molarity** of the solution

*universal gas constant*, usually given as

**absolute temperature**

All you have to do here is rearrange this equation to solve for

Make sure to convert the temperature from *degrees Celsius* to *Kelvin* by using the conversion factor

#color(blue)(|bar(ul(color(white)(a/a)T["K"] = t[""^@"C"] + 273.15color(white)(a/a)|)))#

You will have

#c_"glucose" = Pi/(i * RT)#

#c_"glucose" = (7.7 color(red)(cancel(color(black)("atm"))))/(1 * 0.0821( color(red)(cancel(color(black)("atm"))) * "L")/("mol" * color(red)(cancel(color(black)("K")))) * (273.15 + 25) color(red)(cancel(color(black)("K"))))#

#c_"glucose" = "0.3146 mol L"^(-1)#

Rounded to two **sig figs**, the answer will be

#c_"glucose" = color(green)(|bar(ul(color(white)(a/a)"0.31 mol L"^(-1)color(white)(a/a)|)))#