   Chapter 4, Problem 52PS

Chapter
Section
Textbook Problem

Which of the following methods would you use to prepare 300. mL of 0.500 M K2Cr2O7?(a) Add 30.0 mL of 1.50 M K2Cr2O7 to 270. mL of water.(b) Dilute 250. mL of 0.600 M K2Cr2O7to a volume of 300. mL.

Interpretation Introduction

Interpretation:

It should be determined that the correct method to prepare 300mL of 0.500MK2Cr2O7 from the given methods.

Concept introduction:

• Concentration of solutions can be expressed in various terms; molarity is one such concentration expressing term.
• Molarity (M) of a solution is the number of gram moles of a solute present in one liter of the solution.

Molarity=MassperlitreMolecular massMolarity=W×1000m×V

Where W, V and m are the mass of solute, volume of solution and molar mass of the solute respectively.

W=m×V×M1000

• A solution containing one gram mole or 0.1 gram of solute per litre of solution is called molar solution. A solution containing one gram mole or 0.1 gram of solute per litre of solution is called molar solution.
• Concentrationofsubstance=Amountof substancevolumeofthesubstance
• Amountof substance=Concentrationofsubstance×volumeofthesubstance
Explanation

Amount of K2Cr2O7 in the 250mL solution can be calculated as follows,

AmountofK2Cr2O7 = CK2Cr2O7×VK2Cr2O7 = 0.600 molK2Cr2O7L×250×10-3L = 0.15molK2Cr2O7

0.15molK2Cr2O7 is contained in the new volume of 300 mL of diluted solution.

Therefore the final concentration of the diluted solution is,

ConcentrationofK2Cr2O7,CK2Cr2O7 =0.15molK2Cr2O70.3L = 0.5M

But method a gives K2Cr2O7 concentration of 1.5M

Amount of K2Cr2O7 in the 30

Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started

Calculate your protein RDA.

Understanding Nutrition (MindTap Course List)

Both carbohydrates and protein have 4 calories per gram. T F

Nutrition: Concepts and Controversies - Standalone book (MindTap Course List)

How does a covalent bond form?

Biology: The Dynamic Science (MindTap Course List) 