{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

7-prepn-0026-stdzn-of-base

7-prepn-0026-stdzn-of-base - CHM151LL PREPARATION...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
CHM151LL: P REPARATION & S TANDARDIZATION OF A B ASE S OLUTION | 1 Preparation & Standardization of a Base Solution OBJECTIVES: By performing this experiment, you will learn about solution concentration learn about acid-base titration prepare and standardize a sodium hydroxide solution DISCUSSION: The more solute dissolves in a unit mass or volume of solvent , the higher the solution’s concentration. If the solute is a reactant in a chemical process, then raising its concentration increases the rate of the reaction, and changes the reaction yield if the solute is the limiting reactant. In the chemistry lab, concentration is conventionally expressed as molarity ( M , with units of moles of solute per liter of solution), though we use various convenient alternatives in specific circumstances ( e.g. mole fraction, mass %, volume %, mass/volume %, mg/m 3 , µ g/dL, molality). A solution purchased from chemical companies or prepared for you by the stockroom usually shows the solution’s molar concentration value on the label. Have you ever wondered how these values were measured? Two fundamental approaches exist. In the preparative approach, the supplier or lab technician measures out a known amount of solute (typically by weighing) and then dissolves the solute in enough solvent to make up the desired volume of solution. The second approach, called quantitative analysis , involves measuring the concentration of a solution that was not prepared to a specific value. We measure some physical or chemical property of the solution that changes with solute concentration. Methods include: measuring the solution density (typical for the sulfuric acid solution in car batteries) measuring the interaction of the solution with light (devices measuring refractive index and optical rotation are in widespread use, as are spectrophotometers that measure light absorbed by the solute) measuring the change in some property of the pure solvent (freezing point, boiling point or vapor pressure) evaporating a sample of the solution and weighing the recovered solute, or performing a chemical reaction between a measured volume (called a titer
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern