Practical Techniques

Question 1

Weighing A Solid?

Answer 1

Put the container on the balance and then set the balance to zero,

This eliminates the weight of the container,

Make sure to transfer all the solid out of the reaction vessel so the amount of solid is accurate.

Question 2

Methods To Make Accurate Weighing?

Answer 2

If your dissolving a solid in a solvent to make a solution, you could wash any remaining solid into the new container using the solvent so all the solid you weighed is transferred,

You could re weigh the weighing container after you’ve transferred the solid. This lets you work out exactly how much you added to your experiment.

Question 3

Three Ways To Measure Liquids?

Answer 3

Pipettes,

Burettes,

Measuring Cylinders.

Question 4

Pipettes?

Answer 4

Long, narrow tubes that suck up accurate volumes of liquid,

Pipette filler attached to the end of the pipettes is used so that you can safely control the amount t or liquid your drawing up,

Pipettes are calibrated which reduces transfer errors.

Question 5

Calibrated Means?

Answer 5

The last drop of the liquid stays in the puppets when the liquid is ejected,

This reduces transfer errors.

Question 6

Burettes?

Answer 6

Measure from top to bottom (so when they are filled to the top of the scale, it reads zero),

They have a tap,

You can release it drop by drop,

Take the initial reading and once you’ve released as much liquid as you want, you take the final reading,

The difference is the amount you have used.

Question 7

Measuring Cylinders?

Answer 7

Most common way to measure liquid,

They come in different sizes,

Make sure to use a cylinder of an appropriate size. There is no use using a huge 1000cm3 cylinder to measure 1cm3 of liquid,

This can lead to measurement errors.

Question 8

Gas Syringe?

Answer 8

Measures gasses,

Gases should be measured at room temperature and pressure as the volume of a gas changes with temperature and pressure,

You should also use a gas dyke be that’s the right size for the measurement your making,

Make sure the syringe is completely sealed before using it so that gas cannot escape,

Make sure the gas plunger moves smoothly.

Question 9

Ways To Measure Gas?

Answer 9

Gas syringe,

Counting bubbles (less accurate).

Question 10

How To Collect Gas Being Produced?

Answer 10

Using a gas syringe,

Displacing water from a measuring cylinder.

Question 11

Measuring Temperature?

Answer 11

Use a thermometer,

Make sure the bulb of the thermometer is completely submerged in any substance,

Wait for the temperature to stabilise before taking any initial readings,

Read your measurement at eye level.

Question 12

Measuring Time?

Answer 12

Stopwatch,

They’re more accurate that regular watches,

Always make sure you start and stop the stopwatch at exactly the right time,

You could set an alarm on the stopwatch so you know exactly when to stop an experiment or take a reading,

In physics, you might be able to use a light gate. This will reduce errors and allow for more accurate calculations.

Question 13

Measuring Ph?

Answer 13

Indicators are dyes that change cloud depending on ph,

Universal indicator is a mixture of indicators that changes colour gradually as ph changes. It is useful for estimating ph,

Indicator paper is useful if you don’t want to colour the entire solution that your testing. It changes colour depending on the ph. You could also hold a piece of damp indicator power in a gas sample to test ph,

Ph probes are attached to ph meters which have a digital display that gives a numerical value for the ph of a solution. They’re used to give accurate value of ph.

Question 14

Measure Length?

Answer 14

Ruler,

Depends on what your measuring,

Micrometers are used to measure tiny things like the diameter of a wire,

Ruler should be parallel,

When it’s difficult to measure one length (e.g. water ripple wavelength), you could measure 10 and then divide by 10,

Make sure to measure from the same point on the object when measuring changes in multiple objects length,

You could use a marker to make these accurate,

Make sure to measure at eye level.

Question 15

Measuring Angles?

Answer 15

Protractor,

Alight the vertex (point) or the angle with the mark in the centre of the protractor,

Line up the base line of the protractor with one line that forms the angle,

Extend the line of the angle if it is too short,

Look at the protractor to find angle.

Question 16

Measuring Potential Difference?

Answer 16

If your using an analogue voltmeter, choose the appropriate unit (e.g. V or mV),

If your using a digital voltmeter, you’ll
Most likely be able to switch between them,

Connect the voltmeter in parallel across the component you want to test,

Red wire goes in red bit of voltmeter and black goes in black bit,

Then simply read the potential difference from the screen/scale.

Question 17

Wires Charge?

Answer 17

Red wires are positive,

Black wires are negative.

Question 18

Ammeters?

Answer 18

Measure current,

Choose the most appropriate unit,

Connect the ammeter in series with the component you want to test, making sure they’re both on the same branch,

Again, they usually have red and black ports to show where to connect wires,

Read the current on the screen/scale.

Question 19

Multimeters?

Answer 19

They measure both current and potential difference,

These measure a range of other properties too like resistance,

If you want to find potential difference, connect the red wire in the “V” port,

If you want to find current, comes the red wire in “A” or “mA” port,

The dial in the multimeter should then be turned to the relevant section, e.g. to “A” for current,

The screen will then display.

Question 20

Light Gates Are?

Answer 20

Measure velocity and acceleration,

Sends a beam of light from one side of the gate to a detector on the other side,

When something passes through the gate, the beam of light is interrupted,

The light gate then measures how long the beam was undetected.

Question 21

How To Find Velocity Using A Light Gate?

Answer 21

To find the velocity, connect the light gate to the computer,

Measure the length of the object and input this length using the software,

It will then automatically calculate the velocity of the object as it passes through the beam.

Question 22

How To Find Acceleration Using A Light Gate?

Answer 22

Use an object that interrupts the signal twice in a short period of time,

This can be done by placing a tall piece of card on both ends of the thing your measuring,

The light gate measures the velocity for each section of the object and uses this to calculate the acceleration,

This can be read from computer.

Question 23

Bunsen Burners?

Answer 23

Don’t use it your heating flammable compounds,

Can be easily adjusted to how strong they heat,

Connect the Bunsen to a gas tap and check the hole is closed,

Place on heat proof mat,

Light a split and hold it over Bunsen,

Turn the gas on and the Bunsen will light with a yellow flame,

The more open the hole is, the hotter is gets,

The flame will turn blue if it is all the way open,

The hottest part of the Bunsen is just above the blue cone,

Yellow flame is safer,

If your heating something in a container in the flame, hold it at the top of the flame using tongs,

If your heating something over the flame, you should put a tripod and gauze over the Bunsen burner before you light it.

Question 24

Water Bath?

Answer 24

Is a container filled with water that can be heated to a specific temperature,

Simple water bath can be made by heating a beaker or water over a Bunsen and monitoring the temperature with a thermometer. However, it can be hard to keep this temperature constant,

An electric water bath will monitor and adjust the temperature for you. This is easier and keeps the temperature constant. It is also more accurate.

Question 25

How To Use An Electric Water Bath?

Answer 25

Set the temperature on the water bath and allow the water to heat,

Place the vessel containing your substance in the water bath using test tube holders or tings. The level of the water outside the vessel should be just above the level of the ah stance inside the vessel,

Substance is warmed to the same temperature as the water,

The heating is very even because the water is surrounded by the same heated water,

Water boils at 100 degrees do you can’t use a water bath to eat something to a higher temperature than this because the water will not get hot enough.

Question 26

Electric Heaters?

Answer 26

Often made up of metal plate that can be heated to a certain temperature,

The vessel containing the substance you want to beat is placed on top of the hot plate,

You can heat substances to higher temperatures than you can in a water bath but, as the vessel is only heater from below, you’ll usually have to stir the substance inside to make sure it is evenly heated.

Question 27

Safety Precautions?

Answer 27

Use clamp stands to stop masses falling on toes,

Make sure masses are sensible weight so they don’t break experiment equipment,

Let materials cool before touching then after they have been heated,

Wear insulated gloves to stop you from burning yourself,

If your using an immersion heater, let it dry out before touching it,

If you use a laser, wear safety goggles and never look directly in it. Also make sure you turn it off,

Make sure voltage is not too bright to prevent wires overheating when using electronics,

Handle glasses safely and avoid touching frayed wires.

Question 28

Before Staring An Experiment, You Should?

Answer 28

Write a detailed risk assessment and method,

Draw a labelled diagram to show method to avoid mistakes and accidents,

Draw a scientific drawing where each piece of apparatus is drawn as if your looking at is cross-sectioned.

Question 29

How To Draw Gauze And Heat Proof Mat?

Answer 29

In a scientific drawing, everything is drawn from cross section,

A gauze is drawn like a dotted line and a heat proof mask is just a straight line,

Label them.

Question 30

Working Around Hazardous Chemicals?

Answer 30

Lab coat,

Safety goggles,

Gloves,

Sensible clothing,

Careful they are not flammable,

Work in an area that is well ventilated,

Work in a fume hood if the chemicals could produce nasty gases,

Never directly touch chemicals so use a spatula or containers,

Carefully pour liquids using a funnel to avoid spillages,

Be careful mixing chemicals.

Question 31

Ethical Issues?

Answer 31

Any organisms involved in your investigations need to be treated sexily and ethically,

Animals need to be treated humanely.