Quiz 2 Study Guide

safety - measurement lab

Safety

For Every Lab
  • keep goggles over your eyes until Mr. Leeds says to put them away
  • report all accidents/spills immediately
  • use common sense

In Case of an Emergency

  • nurse ext- 2828

Safety Equipment in Classroom

  • fire extinguisher
  • fire blanket
  • eye wash/shower

Chemicals

  • never taste chemicals
  • always waft liquids
  • never waft solids/powders
  • avoid touching chemicals
  • always wash hands with soap and water after lab
  • if chemicals touch skin- flush with water for 1 minute and notify Mr. Leeds

Glass

  • hot glass and cold glass look the same
  • never use chipped or broken glass
  • never use force to remove or insert glass

Alcohol Burners

  • roll up sleeve, put UP long hair
  • never walk away from a lit burner
  • never point the open end of a hot test tube at yourself or someone else
  • do not look down into a test tube/beaker while it is being heated
  • make sure burner is capped and flame is out when done

End of Experiment

  • clean up area and materials completely
  • make certain that burner is out
  • keep goggles on until Mr. Leeds says to put them away


Post Lab: Reaction in a Bag

red liquid
  • phenol red
  • used as a ph indicator *
  • below 7 turns yellow
  • above 8 turns pink


  • *ph scale-
- measures acidity

- goes from 0-14

-0-7-14

-acid-natural-alkaline

-lemon juice 1.5

-tums 10


two solids

solid a - calcium chloride (calcium and chlorine)

  • acidic
  • hydrotropic- attracted to water (absorbs water)
  • uses-
-canned veggies- keep them firm

-electrolyte in sports drinks

-used to flavor pickles (salty flavors)


solid b- sodium bicarbonate- baking soda

  • hydrotropic
  • not acidici
  • uses-
-baking

-toothpaste

-laundry detergent

-refridgerators


*endothermic = cold

exothermic = hot

POST LAB HEATING BAKING SODA


  • part 1
  • baking soda is being heated and releases a gas
  • the gas is is turned into condensation when it reaches the cooler top of the tube
-foggy, moisture, droplets

  • gas leaves the t. tube
  • goes through the rubber tube into the inverted bottle
  • the pressure starts to increase
  • the water flows out of the inverted bottle


part 2

heated test tube

  • brownish- gold
  • baking soda dissolves


unheated test tube

  • yellowish-gold
  • liquid and solid separated
  • baking soda on bottom
  • tea on top


control group

  • unheated baking soda/tea


experimental group

  • heated baking soda/tea


indicator

  • tea- showed that the heated test tube was not baking soda


variables- a category you try to measure

  • 2 types
-independent variable

+ causes a change in the dependent variable

+ flame/burner (temperature/heat)

- dependent variable

+ tea color


control factors

  • same type of tea
  • amount of baking soda
  • amount of tea
  • same size test tube
  • stir time


experimental errors

  • hole in rubber tube- won't see gas fill bottle
  • stopper is not snug - won't see gas fill bottle
  • not cleaning stirring rod- contaminate


extra question

  • is the amount of condensation more or less than the amount of baking soda being heated?

Less (or same) because the condensation comes from the baking soda and it cannot produce more than itself

1.2 VOLUME NOTES

unit of measure - cm3 (cubic centimeters)


volume- lxwxh (axbxc)


standard unit of length - meter (m)


1 centimeter (1 cm) = 0.01 m

100 centimeter (100 cm) = 1 m


unit cube

  • small cube with 1 cm on each side


volume of liquids-

  • use a graduated cylinder to measure volume *

*always check the intervals or scale


units = milliliters (mL) or cm3

1 mL = 1 cm3

1.7 SINGLE-PAN AND ELECTRONIC BALANCES

  • always zero balance before using it
  • unit of measure = grams
  • pick up by red bar
  • when done put a little weight on balance


BQ'S #1, 3-8, 9-13

1) Why do you think baking soda is used in baking?


- it releases a gas that helps the baked goods rise


3) How many cubic centimeters of water are required to fill a graduated cylinder to the 50.0 mL mark?

- 50 cm3


4) Rectangular box A has a greater volume than rectangular box B but the length of box A is less than the length of Box B. How is this possible?

-the width and height may be greater in box A than box B


5) Adding a stone to a graduated cylinder containing 25.0 cm3 of water raises the water level in the cylinder to the 32.0 cm3 mark. what is the volume of the stone?

-7 cm3


6) a student has a large number of cubes that measure 1 cm along each edge.

a- how many cubes will be needed to build a cube that measures 2 cm along each edge?

--8 cubes


b- how many cubes will be needed to build a cube that measures 3 cm along each edge?

--27 cubes


c- What is the volume, in cubic centimeters, of each of the cubes in (a) and (b)?

-- 8 cm3, 27 cm3


7) one rectangular box is 30 cm long, 15 cm wide, and 10 cm deep. a second rectangular box is 25 cm long, 16 cm wide, and 15 cm deep. which box has the larger volume?

-the second box


8) Figure A shows a cone-shaped graduate used for measuring the volume of liquids. why are the divisions not equally spaced?

- the cone gets larger and opens up as you near the top meaning that the more depth a liquid has the less volume it will have, but the more surface it covers the more volume it has.


9)

a- estimate the positions of arrows i and ii in figure b(a) to the nearest 0.1cm. can you estimate their positions to 0.01cm?

--1.2, 3.8


b- estimate the positions of arrows iii, iV and V in Figure B(b) to the nearest 0.01 cm. can you estimate their positions to the 0.001cm?

-- 1.65, 2.52, 4.30


c- why should you report the positions of the arrows in part (b) to the nearest 0.01 cm and not to the nearest 0.1cm?

--because it shows the millimeter line, so it will be more accurate, and you can only go one place farther than what the scale gives you


10) What part of a cubic centimeter do the smallest divisions on each of the graduated cylinders in Figure C represent? express your answer as a decimal?

- 0.1 cm3, 0.2 cm3


11) what is the level of the liquid in Figure D(a) to the nearest half division? what is the level in Figure D(b) to the nearest half division?

- 4.0 cm3, 1.25 cm3


12) Three students reported the length of a pencil to be 12 cm, 12.0 cm,and 12.00 cm. do all three readings contain the same information?

-yes,

- 11.5-12.4, 11.95- 12.04, 11.995-12.004


13) what advantage is there to making graduated cylinders narrow and tall rather than short and wide?

- easier to read, more depth due to lack of surface, lines further apart