Log in
HomeClass Notes1,200,000US530,000

CHE 1220 Lecture Notes - Lecture 9: Molar Mass, Aluminium Sulfate, Empirical Formula

76 views12 pages
lilacsardine521
21 Feb 2017
School
St. John's University
Department
Chemistry
Course
CHE 1220
Professor
Eranda Maligaspe

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

For addition and subtraction, the answer should have the same number of decimal places as the quantity with the fewest number of decimal places. For multiplication and division, the number of significant figures in the answer should not be greater than the number of significant figures in the least precise measurement. Exact numbers, which come from definitions such as 12 in. 1 mole = 6. 022 1023 items = avogadro"s number = na grams. Model 3: determination of molecular formulas of % mass an element of mass element the present ain sample of mass total sample the. Empirical formula = formula with smallest whole number ratio of atoms of different elements in compound. Molecular formula = some whole number multiple of the empirical formula. Requires molar mass to determine molecular formula from empirical formula: given masses of each element present in a sample, convert mass of each element to moles of each element.

Get access

Grade+
$40 USD/m
Billed monthly
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers
Class+
$30 USD/m
Billed monthly
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
7 Verified Answers

Related Documents

CHEM 1070 Chapter Notes - Chapter 2: Trailing Zero, Scientific Notation, Decimal Mark
CHEM 001 Lecture Notes - Lecture 2: Trailing Zero, Significant Figures, Decimal Mark
graycricket860
L07 Chem 111A Lecture Notes - Lecture 1: Round-Off Error, Significant Figures, Scientific Notation
ivorykoala623

Related Questions


Solve 2 and 3 asap

Part I: What is the complete formula (Salt · x H2O) for the hydrate you will be given in lab?

(25 points)

 

General Procedural guidelines for this lab:

 

  1. From the very beginning of this experiment, only handle the crucible or evaporating dish with crucible tongs. SAFETY: The crucible will be very hot! Never touch the crucible while it could be hot. Use crucible tongs.
  2. Use the same scale throughout this lab.
  3. Do all of your calculations with proper sig figs.
  4. For additions and subtractions, keep the fewest number of decimal places.
  5. For multiplication and division keep the fewest number of significant figures.
  6. While things are heating and cooling, work on Part II of this task.

 

 

Procedure: Watch this video, read along with the following procedure, and take notes: https://www.youtube.com/watch?v=k2s-YG15eIA

 

  1. Wash out a crucible and flame dry. Heat the crucible with a Bunsen burner for 5 minutes on high and let it cool for 10 minutes.

 

  1. Zero the balance.

  2. Mass the crucible and record the mass (with units). __________

 

  1. Fill the crucible about ¾ full with the hydrate.

 

  1. Mass the crucible with the hydrate and record this mass. __________

    Record the color of the hydrate (before heating). __________

 

  1. Heat the crucible with the until all water is driven off. What is left in the crucible is the anhydrate.

    Record the color of the anhydrate (after heating). __________

 

  1. Let the crucible cool for a few minutes (at least 10). Then mass the anhydrate and crucible and

    record this mass. __________

 

  1. Complete the calculations to determine the (i) % mass of water in the hydrate and (ii) the value for x for your hydrate. Show all of your calculations. The calculations for the % mass of water in the hydrate are outlined in the video. You will have to do the calculations for x by yourself. Show all of your calculations on this page or another page.

 

MAKE A DATA TABLE HERE FOR ALL OF YOUR DATA:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MAKE A RESULTS TABLE HERE FOR THE RESULTS OF YOUR CALCULATIONS: