Monday, May 6th: “A” DayTuesday, May 7th: “B” Day

AgendaHomework Questions/Collect: Pg. 248: #1-7Sec. 7.3 quizLab write-up: “Quantitative Determination of

an Empirical Formula”Homework: “More Practice…” worksheet

We will be in the lab next time Please dress appropriately

No Flip-Flops!

Homework Questions/Problems

Sec. 7.3 review, pg. 248: #1-7

You may use your notes, your book, a periodic table, a calculator, your brain, and your 2:00 partner’s brain to complete the quiz…

Good Luck!

Section 7.3 quiz

Lab Partners

Lab Discussion“Quantitative Determination of an

Empirical Formula”Remember, the empirical formula is the simplest

whole-number ratio of elements in a chemical compound.

For example, the ratio of hydrogen atoms to oxygen atoms in H2O

is always 2:1, not 2.5:1 or 1.75:1

“Quantitative Determination of an Empirical Formula”

PurposeIn this lab, you will

React a carefully determined amount of tin, Sn, with excess nitric acid, HNO3, to form a tin-oxygen crystalline product.

Calculate the mole ratio of tin and oxygen in the crystalline product.

Predict an empirical formula for thetin-oxygen product.

“Quantitative Determination of an Empirical Formula”Material Changes

Changes:Cross out the hot plate. We will be using a

bunsen burner set-up, NOT a hot plate.Change forceps to crucible tongs.

Additions:20 mesh granulated tin (Sn)8M nitric acid (HNO3)10 mL graduated cylinder Beaker tongs

“Quantitative Determination of an Empirical Formula”

Additions

“Quantitative Determination of an Empirical Formula”Procedure Changes

Step #1: Make sure to prepare a data table as instructed BEFORE the lab.

Cross out step #2: you will be using a bunsen burner, NOT a hot plate.

Step #3 Addition: After heating/cooling evaporating dish/watch glass cover, measure mass to nearest 0.01g/record in data table!

Step #4: change 30 mesh granulated tin to 20 mesh granulated tin.

Step #5 Addition: Record 3 observations when the nitric acid, HNO3, was added to the tin, Sn.

Step #6 Addition: Record 2 observations when heating dish over the water bath.

Step #8 Addition: Record 2 observations when heating dish over hot flame.

“Quantitative Determination of an Empirical Formula”Procedure Changes

Data TableYou will need to construct a date table as directed

in step #1 in the “Analysis” section. You need to do this BEFORE lab day – I will be checking to make sure you have a table.

Also, you will need to record the following observations:Step #5: 3 observationsStep #6: 2 observationsStep #7: 2 observations

These observations are worth 7 pts!

“Quantitative Determination of an Empirical Formula”

Lab Write-UpTitlePurposeHypothesis: What do you think the empirical

formula for the tin-oxygen product will be?MaterialsProcedure

tin andoxygen

Homework“More Practice with % Composition and

Empirical Formulas” worksheet

For up to 4 points extra credit:NAME the 4 compounds

in each of the problems on the worksheet