IPS Quiz #1

Safety- Measurement Lab

Safety

  • For Every Lab...
  • Keep goggles over eyes until told to put them away
  • report ALL accidents
  • use common sense
  • ICE
  • Nurse ext: 2828
  • Safety Equipment
  • fire extinguisher
  • fire blanket
  • eye wash/shower
  • Chemicals
  • Never taste chemicals
  • waft liquids not solids/powders
  • don't touch chemicals
  • wash hands with soap and water
  • if chemicals touch skin: flush skin under water for 1 minute and tell Mr. Leeds
  • Glass
  • Hot and cold glass look the same
  • don't use chipped or broken glass
  • dispose of broken glass in proper trash
  • never use force to remove or insert glass
  • Alcohol Burners
  • roll up sleeves
  • 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 being heated
  • make sure burner is capped and flame is out when done
  • End of Experiment
  • clean up area and materials completely
  • make certain burner is out
  • keep goggles on until told to put them away


Reaction in a Bag


  • A+Liquid= warm temperature (Exothermic Reaction)
  • B+Liquid= cold temperature (Endothermic Reaction)
  • A+B+Liquid= gas
  • Red Liquid= Phenol Red (used as ph indicator- below 7= yellow; above 8= pink)
  • ph scale: measures acidity; 0-14; 0-6.9= acidic; 7= neutral; 7/1-14= alkaline
  • Solid A= Calcium Chloride
  • acidic
  • hydrotopic- absorbs/attracts water
  • uses: canned veggies (keeps from getting mushy), electrolytes in sports drinks; flavor pickles
  • Solid B= Sodium Bicarbonate (baking soda)
  • not acidic
  • uses: cakes, baking, toothpaste, laundry detergent



Heating Baking Soda

  • Why was there droplets of water at the top of the test tube?
  • Because not all of the gas can escape at once, so the gas that touches the sides of the tube cool down and condensate
  • Where does the gas leaving the tube come from? How do we know this?
  • The gas comes from the heated baking soda
  • We know this because when an empty test tube is heated, not nearly as much gas enters the bottle, so we know that there must be a gas created from the baking soda
  • Control Group- Unheated tube
  • Experimental group- Heated tube
  • Indicator: tea
  • Independent Variable: (causes change in dependent) temperature
  • Dependent variable: color of the tea
  • Control Factors:
  • same type of tea
  • same amount of baking soda
  • same amount of tea
  • same type of test tube
  • same size test tube
  • same stirring time
  • Experimental Errors:
  • hole in rubber tubing
  • stopper is not snug
  • stirring rod is not clean
  • Is the amount of condensation at the top of the test tube more or less than the amount of baking soda heated?
  • Less or equal to, because something can not make more than itself


Box Questions

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

When heated, it releases a gas that allows things to rise.


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

50 cm3


4. How is it possible for a box with a greater volume than another to have a length less than the other?

The height or width of the first box is greater.


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

7cm3 (called displacement)


6. With cubes that measure 1 cm along each edge how many cubes will be needed to build a cube that measures....


a. 2cm along each edge?

8 cubes

b. 3 cm along each edge?

27 cubes

c. What is the volume of the two cubes made above?

8cm3 and 27cm3


7. Which has a larger volume: 30 cm long, 15 cm wide, and 10 cm deep vs. 25 cm long, 16 cm wide, and 15 cm deep?

25x16x15 cm3

8. Why are divisions on a cone shaped graduated cylinder not equally spaced?

There is a greater surface area at the top versus the bottom, so it will take more depth to measure a smaller number versus a larger one.


Things to remember...


  • only estimate one decimal place past what you can see
  • find intervals of graduated cylinder before measuring
  • measure volume of water from bottom of meniscus
  • When rounding: "4 and below let it go 5 and above give it a shove"
  • the more surface area in a container/graduated cylinder, the less depth required to reach a certain amount (lines are closer together)



Volume

  • use a graduated cylinder
  • always check intervals before measuring
  • mL or cm3
  • 1 mL = 1cm3
  • read the bottom of the meniscus


Single Pan Balance Notes

  • check that pan is clean and dry
  • zero balance before each massing
  • never switch pans
  • hold by red bar only