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HCL is used to distinguish between Al and Pb ......Pb gives an insoluble PbCl2 .....while Al dissolves i guess in excess
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AS Chemistry PRACTICAL 33
- Thread starter Muffy94
- Start date
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can u plzzz get for 34 chem and bio ?/no prob!
and if possible 33 phy also ?
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or just add the sample to Potassium Iodide. if Pb ions are there, they will form a yellow precipitate...if Al ions are there, there will be no precipitate.
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One more doubt..
When recording the burette readings, to what accuracy are we supposed to write the readings? The marking scheme says 0.05 cm3.. how would that be? Please give an example..
When recording the burette readings, to what accuracy are we supposed to write the readings? The marking scheme says 0.05 cm3.. how would that be? Please give an example..
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A
s the smaalest reading that can be taken is 0.1 cm3 hence the uncertainity is 1/2 of that smallest reading in every appratus.
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Hey! after 2009 the 3 questions in p3 are extincted
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http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_31.pdf
Please help me with question no. 1 c iii.. I don't know what to do :/
Please help me with question no. 1 c iii.. I don't know what to do :/
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supposing u got a titre reading of 21.4....u have to change it to 0.05(which is 2dp).....so u hv to either write 21.45 or 21.40
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what??? r u sure?
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Help!!!
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roadtrip9o9 I hope you saw this
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Tips for drawing the graphs:
· Think carefully before choosing scales for the axes, you need to keep in mind that the scale needs your values to cover at least half of the page and should is sensible, by that I mean you should be able to easily find values on the axes without needing to calculate what value some point on the axes represent.
· Sharp your pencil, the last thing you want is to lose marks because your line was too thick.
· Double check when marking the points, 1 mistake and in some cases you might mess up the whole graph.
· "Line of best fit." Doesn't necessarily mean that its a straight line. Although rarely, it could be a curve too that fits most of the points.
· In graphs of experiments like heating and then cooling, you need to draw two lines, 1 representing cooling and the other one representing heating instead of a curve.
· Whenever they ask you to find gradient, ALWAYS draw a triangle, and the bigger the triangle, the more accurate your gradient.
· If you have doubt about your gradient, just take any point that is close to the line and find (y/x), this value should be very close to the gradient found using the triangle. But remember this only works when the graph is starting from origin or near it.
· Try to never break your graph but if you do, REMEMBER that the y-intercept needs to be calculated using the equation "y = mx + c" where m is the gradient you found, c is the y-intercept and can be found using the y and x value of any point on the lane.
· Try to keep your graph clean and visible. If you need multiple lines to find gradient and other value, make sure they're distinguishable.
· ALWAYS write what each axis represents with its unit.
· To determine which quantity goes on the x and y axis, you need to find which quantity is dependent and which one is independent. Independent is usually the one you are changing and dependent is the one you measure.
· If you draw multiple graphs, make sure to label them.
· Don't spend more than 15 minutes on the graph. The graph is usually simple, and if its not then you've done probably something wrong and instead of wasting time on it, try to score marks in other parts first and then come in the end to figure out what's the problem with the graph.
· If you're good at salt analysis, then do it first and finish it fast so you can do the graphing without any tension.
· REMEMBER even if you draw the graph wrong due to some wrong measurements or something, don't lose hope on it, you can still workout the rest of the questions for the wrong graph and score most of those marks like gradient and stuff.
· When they ask you to prove some relationship like T=kV or something, write that since the graph is a straight line, the value of the K is constant and therefore the relationship is true...unless emm...your line is not straight.
If you don't have time to draw the graph, try to do as much as you can like plotting two or three values and
· Think carefully before choosing scales for the axes, you need to keep in mind that the scale needs your values to cover at least half of the page and should is sensible, by that I mean you should be able to easily find values on the axes without needing to calculate what value some point on the axes represent.
· Sharp your pencil, the last thing you want is to lose marks because your line was too thick.
· Double check when marking the points, 1 mistake and in some cases you might mess up the whole graph.
· "Line of best fit." Doesn't necessarily mean that its a straight line. Although rarely, it could be a curve too that fits most of the points.
· In graphs of experiments like heating and then cooling, you need to draw two lines, 1 representing cooling and the other one representing heating instead of a curve.
· Whenever they ask you to find gradient, ALWAYS draw a triangle, and the bigger the triangle, the more accurate your gradient.
· If you have doubt about your gradient, just take any point that is close to the line and find (y/x), this value should be very close to the gradient found using the triangle. But remember this only works when the graph is starting from origin or near it.
· Try to never break your graph but if you do, REMEMBER that the y-intercept needs to be calculated using the equation "y = mx + c" where m is the gradient you found, c is the y-intercept and can be found using the y and x value of any point on the lane.
· Try to keep your graph clean and visible. If you need multiple lines to find gradient and other value, make sure they're distinguishable.
· ALWAYS write what each axis represents with its unit.
· To determine which quantity goes on the x and y axis, you need to find which quantity is dependent and which one is independent. Independent is usually the one you are changing and dependent is the one you measure.
· If you draw multiple graphs, make sure to label them.
· Don't spend more than 15 minutes on the graph. The graph is usually simple, and if its not then you've done probably something wrong and instead of wasting time on it, try to score marks in other parts first and then come in the end to figure out what's the problem with the graph.
· If you're good at salt analysis, then do it first and finish it fast so you can do the graphing without any tension.
· REMEMBER even if you draw the graph wrong due to some wrong measurements or something, don't lose hope on it, you can still workout the rest of the questions for the wrong graph and score most of those marks like gradient and stuff.
· When they ask you to prove some relationship like T=kV or something, write that since the graph is a straight line, the value of the K is constant and therefore the relationship is true...unless emm...your line is not straight.
If you don't have time to draw the graph, try to do as much as you can like plotting two or three values and
Precipitation reactionsCan anybody PLEASE help me with the order of reagents that they usually ask in the cation anion test?
i have no idea which reagent is to be used after what and which order would give incorrect result
eg.reagent 1: to identify any carbonate ion present
reagent 2: to identify any chloide ions present
now i know the answers but can someone actually explain the logic behind the order and all?
Any guidance regarding this would be highly sppreciated
IF you are required to identify a salt, or an ion, say the sulfate ion, you add barium nitrate. Barium sulfate is insoluble and so you will see a white ppt.
The reason? If you have a salt (e.g Sodium sulfate) and you add another salt (barium nitrate) they exchange:
aX + bY ==> bX + aY
so it becomes sodium NITRATE and barium SULFATE
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chiilax ! good luck to all chem peeps !!!!!
!!!!!
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thank you
Precipitation reactions
IF you are required to identify a salt, or an ion, say the sulfate ion, you add barium nitrate. Barium sulfate is insoluble and so you will see a white ppt.
The reason? If you have a salt (e.g Sodium sulfate) and you add another salt (barium nitrate) they exchange:
aX + bY ==> bX + aY
so it becomes sodium NITRATE and barium SULFATE
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how do you know?
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hmm , hi guys
I have a small question
how are we supposed to study for p3 ? I really have no idea what to do or how to prepare ><"
I'm lost any help is really appreciated
I have a small question
how are we supposed to study for p3 ? I really have no idea what to do or how to prepare ><"
I'm lost
any help is really appreciated
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read the thread, u'll understandhmm , hi guys
I have a small question
how are we supposed to study for p3 ? I really have no idea what to do or how to prepare ><"
I'm lost