Chemistry, 02.10.2019 02:00, Trevon0906

An analytical chemist weighs out 0.188 g of an unknown triprotic acid into a 250 ml volumetric flask and dilutes to the mark with distilled water. he then titrates this solution with 0.0600 m naoh solutions. when the titration reaches the equivalence point, the chemist finds he has added 95.9 ml of naoh solution.

calculate the molar mass of the unknown acid.

Answers: 2

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answered: theresaeleanor

The molar mass of unknown triprotic acid is 97.66 g/mol

Explanation:

To calculate the molarity of acid, we use the equation given by neutralization reaction:

n_1M_1V_1=n_2M_2V_2

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of triprotic acid

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is NaOH.

We are given:

$n_1=3\\M_1=?M\\V_1=250mL\\n_2=1\\M_2=0.0600M\\V_2=95.9mL$

Putting values in above equation, we get:

$3\times M_1\times 250=1\times 0.0600\times 95.9\\\\M_1=0.0077M$

To calculate the molecular mass of solute, we use the equation used to calculate the molarity of solution:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

We are given:

Molarity of solution = 0.0077 M

Given mass of triprotic acid = 0.188 g

Volume of solution = 250 mL

Putting values in above equation, we get:

$0.0077M=\frac{0.188\times 1000}{\text{Molar mass of triprotic acid}\times 250}\\\\\text{Molar mass of triprotic acid}=97.66g/mol$

Hence, the molar mass of unknown triprotic acid is 97.66 g/mol

answered: Guest

water molecules stay close to each other through cohesion, the collective action of hydrogen bonds between water molecules. cohesion plants draw water upwards from the root through the stem's transport tubes (xylem) to the leaf. this transport occurs even in large trees and against gravity. transpiration, evaporation of water from plant leaves, creates a tension on water molecules being pulled up from the stem and roots.

water also has high (the attraction of one substance to another) properties because of its polar nature. adhesion of water molecules to plant cell walls counteract gravity while water is transported from roots to leaves.

water exhibits a very high surface tension when compared to other liquids. surface tension is a property of a liquid that holds the surface together and allows it to resist an external force. by capillary action, the water forms concave menisci inside the pores. the high surface tension of water pulls the concavity outwards, generating enough force to lift water from the roots to the leaves of plants.

thus, cohesion, along with adhesion and surface tension creates a capillary action that keeps water molecules interacting and moving through the plants out to the leaf cells.

therefore, option d) is the correct answer.

explanation:

answered: Guest

Answer is to avoid experimental error