Safety in science lessons. How to stay safe in science lessons

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1 Safety in science lessons How to stay safe in science lessons

2 Students must not enter a laboratory without permission

3 Sensible and safe behaviour is expected at all times Be angelic!

4 Students must not eat or drink in a laboratory You might get poisoned!

5 Apparatus must not be touched or used without permission You might damage it!

6 Bags and coats must be stored safely or, you might trip over them!

7 Goggles must be worn and long hair tied back when instructed

8 All accidents and damage must be reported immediately to the teacher

9 All apparatus must be returned carefully and safely after practical work It keeps the technician happy!

10 Bench surfaces must be clean and dry at the end of the lesson

11 Obey any instructions given by a member of staff They may stop you from doing something silly!

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17 Measuring the volume of irregular objects All matter takes up space, so all matter has volume. A tool used to measure volume is the graduated cylinder The graduated cylinder measures the volume of liquids in milliliters (ml) 1 ml is equal to 1 cubic centimeter (cc) Some objects have a regular shape, like cereal boxes and bars of soap To measure the volume of a regular shaped object, you use the formula volume = length x width x height Some objects have an irregular shape, like rocks and pencils To measure the volume of irregularly shaped objects, you must use the water displacement method The water displacement method makes use of the fact that two objects cannot be in the same place at the same time

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19 Meniscus Madness

20 - A characteristic of liquids in glass containers is that they curve at the edges. - This curvature is called the meniscus. With water in glass, the meniscus will curve up at the edges and down in the center so we say you read the bottom of the meniscus. You measure the level at the horizontal center or inside part of the meniscus.

21 When measuring liquid volume it is important to read the graduated cylinder correctly. You eye should be level with the top of the liquid and you should read the bottom of the meniscus.

22 You would read this as 18mL and not 18.5 ml.

23 In some plastic cylinders water has a flat surface. In that case top or bottom doesn't matter, but we can still say use the center rather than the edges

24 What is the scale of this graduated cylinder? 5 ml 10 graduations.2 ml/ graduation

25 How may ml is showing in this graduated cylinder? 73 ml

26 How may ml is showing in this graduated cylinder? 73 ml

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28 11.5 ml

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30 52.9 ml

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32 6.6 ml

33 You can also get a meniscus that rises up instead of dipping down at the surface. This is an example that shows how a meniscus can rise up instead of going down.

34 Reading the Volume from a 100-mL Graduated Cylinder Step 1: Determine the scale increment: To find the scale increment, subtract the values of any two adjacent labeled graduations and divide by the number of intervals (60mL-50mL) What is the scale increment for the 100-mL graduated cylinder? 10 ml 10 lines In the 100-mL graduated cylinder shown, the labeled graduations are 60 and 50 ml. So, subtract 60 ml - 50 ml = 10 ml. Next, count that there are ten intervals between the labeled graduations. Therefore, the scale increment is 1 ml/graduation.

35 Images created at Measuring Liquid Volume What is the volume of water in each cylinder? Pay attention to the scales for each cylinder.

36 n/syllabus/unit14/new/testingmain1.htm Measuring Solid Volume 9 cm We can measure the volume of regular object using the formula length x width x height. 10 cm 8 cm X X = We can measure the volume of irregular object using water displacement. Amount of H 2 O with object = About of H 2 O without object = Difference = Volume = Click here for an online activity about volume. Choose Lessons Volume & Displacement

37 There is also a meniscus in your knee, but don t get that one confused by this other meaning.

38 Using a Triple Beam balance Mass is the measure of how much matter an object contains. We measure mass in units of grams (g), specifically (kg) Weight is the downward pull on an object due to gravity. is measured using a scale. is measured using pounds (lbs) or Newtons (N)

39 DEFINITIONS Mass- the amount of matter an object has. Matter- something that has mass and takes up space. Weight- is the amount of mass of an object, it is dependent upon gravity.

40 Units for Measuring Mass Mass is measured in grams and kilograms. 1 paper clip= 1 gram 1000g=1 kilogram The average human adult weighs 75kg.

41 Tools for Measuring Mass **The Triple Beam Balance is the tool we use to measure mass.

42 How to use a Triple Beam Balance 1. Make sure the balance scale is at zero. 2. Place the object to be weighed on the balance plate and move the largest RIDER one notch at a time until the beam drops. Move the rider back one notch until it locks into place.

43 3. Move the next largest rider until the beam drops. Back it up one notch, and lock it in place. 4. Move the smallest rider until the beam swings equally above and below the zero mark.

44 ADD UP ALL THE NUMBERS AND THAT WILL GIVE YOU THE MASS! **Always remember to write the unit of mass down. (ex.- kg, g)**

45 COMPARE AND CONTRAST MASS vs. WEIGHT Always remains constant Depends on gravity Does not depend on gravity weight=mass x gravity weight of an object changes if the gravity changes

46 When we measure the mass of an object we compare it s mass to that of a know mass using a triple beam balance.

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54 The Bunsen burner Invented by Robert Wilhelm Bunsen Circa 1855

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56 Air hole closed: a yellow, sooty flame often called the safety flame. Air hole slightly open Air hole half open Air hole fully open: very hot roaring blue flame

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59 In order to have a fire, there must be three elements: Fuel -- something which will burn Heat -- enough to make the fuel burn Air -- more specifically, oxygen

60 SAFETY Burns from a Bunsen burner are the most common lab accidents Temperatures are very hot and at NO TIME should you PLAY with the flame. Long hair MUST be tied back. Hair is VERY flammable. SAFETY GLASSES MUST be worn at ALL TIMES.

61 SAFETY Make sure that NO FLAMMABLE objects are near the lit Bunsen Burner. If you burn yourself, place the burned area under cold water and tell a teacher.

62 The Flames of the Bunsen Burner Non- Luminous With the Air Hole OPEN Un-burnt gas This flame is very HOT

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64 Tap Closed Tap Open

65 Luminous Bunsen Flame This flame is: 1. Yellow 2. Silent 3. Visible 4. Cool 5. Sooty 6. Safe The "coolest" flame is a yellow / orange color. It is approximately 300 C. It is never used to heat anything, only to show that the Bunsen burner is on. It is called the safety flame. The Air-hole is CLOSED

66 Roaring Flame: Non- Luminous This flame is: 1. Blue 2. Noisy 3. Non-luminous 4. Very hot 5. Clean 6. Dangerous if left unattended The Air-hole is OPEN The hottest flame is called the roaring blue flame. It is characterized by a light blue triangle in the middle and it is the only flame of the 3 which makes a noise. It is approximately 700 C.