practicals Flashcards

1
Q

What is mol/dm^3 in a titration equation?

A

This is the concentration

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2
Q

what is dm^3

A

decimetres cubed

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3
Q

what must you do to any unit to make it decimetres cubed-dm^3

A

divide the number by 1000 to make it decimetres cubed

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4
Q

What is the aim of titration?

A

The aim of titration is to find out the titrant. This is the amount of known solution added (usually an acid) to the unknown solution (usually alkali),you must add the known concentration until the solution turns neutral,you use this unit of added acid to work out the concentration of the unknown solution.

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5
Q

Why do we need to find out the titrant?

A

The titrant is used to figure out the concentration in the uknown solution in an equation.

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6
Q

what is dm^3 usually used to measure in the equations>

A

concentration=mol/dm^3 or volume=dm^3

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7
Q

What is a neutral colour for the indicator for phaenolphaelin

A

colourless

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8
Q

What is a neutral colour for Methyl Orange

A

Yellow

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9
Q

What is a constituent?

A

A consituent is a part of something

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10
Q

What is the goal of electrolysis?

A

It is the use of an electrical current to break down compounds containing ions,into their constituent elements.

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11
Q

What is the substance being broke down called in electrolysis?

A

Electrolytes

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12
Q

What are the electrodes made from?

A

Solids that conduct electricity

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13
Q

Where do the positively charged ions go to during electrolysis?

A

the cathode (negative electrode)

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14
Q

Where do negatively charged ions go in electrolysis?

A

The Anode (the positive electrode)

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15
Q

What is the difference between compounds and mixtures?

A

compounds are chemicallybonded and mixtures are not.

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16
Q

What does electrolysis seperate/break down?

A

Ionic compounds

17
Q

When can ionic compounds conduct electricity?

A

When they are molten or dissolved in water

18
Q

What is different when metals are more reactive than carbon?

A

They can be extracted from their ores using electrolysis

19
Q

Is electrolysis expensive or cheap?

A

Expensive

20
Q

What makes electrolysis expensive?

A

the high ammount of heat and electrical energy needed

21
Q

What is an endothermic reaction?

A

Taking in energy

22
Q

What is an exothermic reacton?

A

LEtting out energy,warming the environment.

23
Q

How many cm^3 of Hydrochloric acid is used in the changing temperatures practical?

A

30 cm^3

24
Q

IN the changing temperatures practical what is used to hold the hydrochloric acid? and what is this item holding the acid placed inside and why?

A

The polstyrene cup is holding the acid and is placed inside a beaer to stop it from falling over.

25
Q

what happens next after you put the acid into the cup and the cup into the beaker in the changing temp practical?

A

Using a thermometre,measure the temp (C) of the acid and the place 5cm^3 of sodium hydroxide into the cup and put a lid on with a small hole in it.

26
Q

What must you do after putting the lid on in the changing temp practical?

A

Put the thermometre through the hole in the lid and use the themometre to swirl,due to this being an exothermic reaction we look carefully at the temperature rise.

27
Q

What do you do when the reading on the thermometre stops increasing in the changing temp practical?

A

You record the highest temperature reached.Then repeat the experimetn wit 10 cm^3, of sodium hydroxide solution and repeat the experiment several more times,incrementally increasing the sodium hyydroxide solution by 5cm^3 each time.

28
Q

in the changing temp practical after rpeating the experiment,each time with 5cm^3 added,at what point do we stop and what do we do then?

A

We stop when we have added 40cm^3 and done the reaction,and we repeat the whole experiment one more time so you have two sets of results.

29
Q

in the changing temp practical after getting our two sets of results what do we do?

A

We calculate a mean of all the maximum heat values and make a chart,showing an increase and then a slow,sloping decrease.

30
Q

in the changing temp practical why doe the chart begin to decrease?

A

As ast first,when the chart is steep the hydrochloric acid and sodium hydroxide are reacting weel,andheating up,but when there is tooo much sodium hydroxide,as we are adding in increments each time,there isnt enough hydrochloric acid to react and some sodium hydroxide cant react.

31
Q

in the changing temp practical why do we use polystyrene cups,and a lid?

A

As polystyrene is a good thermal insualtor and the lid reduces heat loss.

32
Q

In the chart in the changing temp practical there is a maximum reached point due to…

A

SOme sodium hydroxide not being able to react as all of the hydrochloric acid has already reacted with other sodium hydroxide.

33
Q

in the changing temp practical why does the overall temperature decrease instead of staying at the greatest possible temperature?

A

The unreacted sodium hydroxide that is added does not react and heat up,so the room temperature sodium hydroxide cools down the temperature of the cup gradually.