A student heats a test tube containing a large amount of protein and biuret reagent. She notices a color change from violet to blue. Explain why heating causes a color change

Explanation:

Proteins are formed from amino acids that are held together by peptides bonds. We have excess of protein present with Biuret reagent which is a combination of sodium hydroxide(NaOH) and copper sulfate(CuSO4)

The normal color of biuret reagent is blue but when we have protein present in biuret reagent its color will be Violet and when we heat this the protein present in it will gain molecular energy disrupting the peptides bonds present as a result the color changes now to blue which is the original color of the biuret solution this happened because biuret test was used to detect proteins or peptide bond specifically but now they are disrupted hence the color change.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"