Question

Creatinine, , is a by-product of muscle metabolism, and creatinine levels in the body are known to be a fairly reliable indicator of kidney function. The normal level of creatinine in the blood for adults is approximately 1.0 mg per deciliter (dl) of blood. If the density of blood is 1.025 g/ml, calculate the molality of a normal creatinine level in a 60.0-ml blood sample.

Answer 1

Answer;

Molarity = 88.25 μmol/L

Explanation;

The creatinine has a concentration of 1 mg / deciliter or 10 mg / liter of blood.

( 1 dL = .1L)  

note; we don't need the volume of the sample  

1 liter of blood weighs 1025 g so mg creatinine / kg of blood

= 10 x 1000 / 1025 = 9.756 mg creatinine / kg of blood  

Molecular weight of C4H7N3O is 113.12 g/mol  

moles of creatinine = 9.756 / 113.12 = 0.0862 / kg  

molality of the creatinine in blood = 8.62 X 10 ^ -5 mol / Kg of blood  

or 86.2 x 10 ^ -6 mol / kg or 86.2 μmol/ Kg  

86.1 * 1.025 μmol/ L = 88.25μmol/ L

Molarity = 88.25 μmol/L