Monthly Archives: February 2012

IP Ratings explained

IP RATING TABLE
Degree of Protection
1st Digit(Solid Objects)
2nd Digit(Liquids)
0
No Protection
No Protection
1
Protected against objects
larger than 50mm
Drip Proof
2
Protected against objects
larger than 12mm
Protected against direct sprays
of water up to 15° from vertical
3
Protected against objects
larger than 2.5mm
Protected against direct sprays
of water up to 60° from vertical
-light rain proof
4
Protected against objects
larger than 1mm
Protected against water sprayed
from all directions-light splash proof
5
Protected against dust
limited ingress
Protected against low pressure
jets of water from all directions
-limited ingress permitted
6
Totally protected against dust
Protected against low pressure
jets of water (use on ship deck)
-limited ingress permitted
7
Not Defined
Protected against the effect
of immersion between
150mm & 1 metre
8
Not Defined
Protected against long periods
of immersion under pressure

pH Measurement theory and Electrodes

pH Measurement
The measurement of pH using a pH Electrode is an age old method that centres around
the perception of a substance as acidic or alkaline and is dependent on the concentration
of the hydrogen Ion (H+) within the substance.

The use of a pH electrode allows this measurement to be expressed in a meaningful way.
Derived from the Sorensen Equation the pH value is defined as a negative logarithm of the H+ concentration in a given solution.
A high H+ Concentration equals: 1mol/L = 10o pH = 0 (ACIDIC)
A low H+ Concentration equals: 10-14 mol/L pH=14 (ALKALINE)
It is therefore simple to measure the pH of a substance and compare it with other substances. pH 0 is extremely acidic, pH 14 is extremely alkaline and pH 7 neutral.
Measuring pH Values
Measuring the pH of a substance requires the use of a pH Electrode and a Reference Electrode. The pH Glass at the end of the electrode acts as the sensing part of the circuit.

The second part of the circuit is the reference electrode. This is a stable point that has a defined potential and is independent of the solution to be measured. The reference electrode fig is made up of a reference element that is commonly a Silver/Silver Chloride wire encased in a known electrolyte. The reference electrode then has a junction, which is the contact between the stable internal reference electrode and the solution to be measured. This is commonly a porous ceramic pin.

The evolution of pH electrodes came with the joining of the two separate electrodes to produce the COMBINATION pH ELECTRODE. The formation of the combination electrode can be seen below. The formation of the combination electrode still has the pH Glass membrane acting in the same way. The reference electrode is continually encased around the pH electrode. As the pH Glass comes into contact with an aqueous substance to measure, a gel layer forms on the membrane. This also happens on the inside of the glass layer. The pH value of the aqueous solution will either force Hydrogen Ions out of the Gel layer or into this layer. The Internal buffer in the glass electrode has a constant pH value and this keeps the potential at the inner surface of the membrane constant. The membrane potential is therefore the difference between the inner and outer charge. If you then factor in the reference electrode with its stable potential you have a combination pH electrode that encapsulates the measuring electrode and reference electrode.

P&R Labpak are able to offer a huge range of electrodes and through it’s electrode supplier Sentek can offer their equivalents which are less expensive and yet are the same or better quality.  Contact us on 0870 034 2055 or e-mail us at sales@prlabs.co.uk with your electrode enquiries.

 
How the pH Electrode Works
As the pH Glass comes into contact with an aqueous substance to measure, a gel layer forms on the membrane.
This also happens on the inside of the glass layer.
The pH value of the aqueous solution will either force Hydrogen Ions out of the Gel layer or into this layer.
The Internal buffer in the glass electrode has a constant pH value and this keeps the potential at the inner
surface of the membrane constant.

The membrane potential is therefore the difference between the inner and outer charge.
If you then factor in the reference electrode with its stable potential you have a combination
pH electrode that encapsulates the measuring electrode and reference electrode.

Visit www.prlabs.co.uk for more information or to contact us.  Check out our news pages for special offers – www.prlabs.co.uk/news

Whatman filter papers – Which one to use?

The download link below is a pdf document detailing which Whatman filter papers to use for which application.  Just click on the link below.

PDF download

If you require any help with filtration just contact our sales desk – sales@prlabs.co.uk or call us on 0870 034 2055.

Alternative Chemical Names

Below is a list of common chemical names and their actual chemical name.

Common Chemical Names

Common Name
Chemical Name
acetone
dimethyl ketone; 2-propanone (usually known as acetone)
acid potassium sulfate
potassium bisulfate
acid of sugar
oxalic acid
ackey
nitric acid
alcali volatil
ammonium hydroxide
alcohol, grain
ethyl alcohol
alcohol sulfuris
carbon disulfide
alcohol, wood
methyl alcohol
alum
aluminum potassium sulfate
alumina
aluminum oxide
antichlor
sodium thiosulfate
antifreeze
ethylene glycol
antimony black
antimony trisulfide
antimony bloom
antimony trioxide
antimony glance
antimony trisulfide
antimony red (vermillion)
antimony oxysulfide
aqua ammonia
aqueous solution of ammonium hydroxide
aqua fortis
nitric acid
aqua regia
nitrohydrochloric acid
aromatic spirit of ammonia
ammonia in alcohol
arsenic glass
arsenic trioxide
azurite
mineral form of basic copper carbonate
asbestos
magnesium silicate
aspirin
acetylsalicylic acid
baking soda
sodium bicarbonate
banana oil (artificial)
isoamyl acetate
barium white
barium sulfate
benzol
benzene
bicarbonate of soda
sodium hydrogen carbonate or sodium bicarbonate
bichloride of mercury
mercuric chloride
bichrome
potassium dichromate
bitter salt
magnesium sulfate
black ash
crude form of sodium carbonate
black copper oxide
cupric oxide
black lead
graphite (carbon)
blanc-fixe
barium sulfate
bleaching powder
chlorinated lime; calcium hypochlorite
blue copperas
copper sulfate (crystals)
blue lead
lead sulfate
blue salts
nickel sulfate
blue stone
copper sulfate (crystals)
blue vitriol
copper sulfate
bluestone
copper sulfate
bone ash
crude calcium phosphate
bone black
crude animal charcoal
boracic acid
boric acid
borax
sodium borate; sodium tetraborate
bremen blue
basic copper carbonate
brimstone
sulfur
burnt alum
anhydrous potassium aluminum sulfate
burnt lime
calcium oxide
burnt ochre
ferric oxide
burnt ore
ferric oxide
brine
aqueous sodium chloride solution
butter of antimony
antimony trichloride
butter of tin
anhydrous stannic chloride
butter of zinc
zinc chloride
calomel
mercury chloride; mercurous chloride
carbolic acid
phenol
carbonic acid gas
carbon dioxide
caustic lime
calcium hydroxide
caustic potash
potassium hydroxide
caustic soda
sodium hydroxide
chalk
calcium carbonate
Chile saltpeter
sodium nitrate
Chile nitre
sodium nitrate
Chinese red
basic lead chromate
Chinese white
zinc oxide
chloride of soda
sodium hypochlorite
chloride of lime
calcium hypochlorite
chrome alum
chromic potassium sulfate
chrome green
chromium oxide
chrome yellow
lead (VI) chromate
chromic acid
chromium trioxide
copperas
ferrous sulfate
corrosive sublimate
mercury (II) chloride
corundum (ruby, sapphire)
chiefly aluminum oxide
cream of tartar
potassium bitartrate
crocus powder
ferric oxide
crystal carbonate
sodium carbonate
dechlor
sodium thiophosphate
diamond
carbon crystal
emery powder
impure aluminum oxide
epsom salts
magnesium sulfate
ethanol
ethyl alcohol
farina
starch
ferro prussiate
potassium ferricyanide
ferrum
iron
flores martis
anhydride iron (III) chloride
fluorspar
natural calcium fluoride
fixed white
barium sulfate
flowers of sulfur
sulfur
‘flowers of’ any metal
oxide of the metal
formalin
aqueous formaldehyde solution
French chalk
natural magnesium silicate
French vergidris
basic copper acetate
galena
natural lead sulfide
Glauber’s salt
sodium sulfate
green verditer
basic copper carbonate
green vitriol
ferrous sulfate crystals
gypsum
natural calcium sulfate
hard oil
boiled linseed oil
heavy spar
barium sulfate
hydrocyanic acid
hydrogen cynanide
hypo (photography)
sodium thiosulfate solution
Indian red
ferric oxide
Isinglass
agar-agar gelatin
jeweler’s rouge
ferric oxide
killed spirits
zinc chloride
lampblack
crude form of carbon; charcoal
laughing gas
nitrous oxide
lead peroxide
lead dioxide
lead protoxide
lead oxide
lime
calcium oxide
lime, slaked
calcium hydroxide
limewater
aqueous solution of calcium hydroxide
liquor ammonia
ammonium hydroxide solution
litharge
lead monoxide
lunar caustic
silver nitrate
liver of sulfur
sufurated potash
lye or soda lye
sodium hydroxide
magnesia
magnesium oxide
manganese black
manganese dioxide
marble
mainly calcium carbonate
mercury oxide, black
mercurous oxide
methanol
methyl alcohol
methylated spirits
methyl alcohol
milk of lime
calcium hydroxide
milk of magnesium
magnesium hydroxide
milk of sulfur
precipitated sulfur
“muriate” of a metal
chloride of the metal
muriatic acid
hydrochloric acid
natron
sodium carbonate
nitre
potassium nitrate
nordhausen acid
fuming sulfuric acid
oil of mars
deliquescent anhydrous iron (III) chloride
oil of vitriol
sulfuric acid
oil of wintergreen (artificial)
methyl salicylate
orthophosphoric acid
phosphoric acid
Paris blue
ferric ferrocyanide
Paris green
copper acetoarsenite
Paris white
powdered calcium carbonate
pear oil (artificial)
isoamyl acetate
pearl ash
potassium carbonate
permanent white
barium sulfate
plaster of Paris
calcium sulfate
plumbago
graphite
potash
potassium carbonate
potassa
potassium hydroxide
precipitated chalk
calcium carbonate
Prussic acid
hydrogen cyanide
pyro
tetrasodium pyrophosphate
quicklime
calcium oxide
quicksilver
mercury
red lead
lead tetraoxide
red liquor
aluminum acetate solution
red prussiate of potash
potassium ferrocyanide
red prussiate of soda
sodium ferrocyanide
Rochelle salt
potassium sodium tartrate
rock salt
sodium chloride
rouge, jeweler’s
ferric oxide
rubbing alcohol
isopropyl alcohol
sal ammoniac
ammonium chloride
sal soda
sodium carbonate
salt, table
sodium chloride
salt of lemon
potassium binoxalate
salt of tartar
potassium carbonate
saltpeter
potassium nitrate
silica
silicon dioxide
slaked lime
calcium hydroxide
soda ash
sodium carbonate
soda nitre
sodium nitrate
soda lye
sodium hydroxide
soluble glass
sodium silicate
sour water
dilute sulfuric acid
spirit of hartshorn
ammonium hydroxide solution
spirit of salt
hydrochloric acid
spirit of wine
ethyl alcohol
spirits of nitrous ether
ethyl nitrate
sugar, table
sucrose
sugar of lead
lead acetate
sulfuric ether
ethyl ether
talc or talcum
magnesium silicate
tin crystals
stannous chloride
trona
natural sodium carbonate
unslaked lime
calcium oxide
Venetian red
ferric oxide
verdigris
basic copper acetate
Vienna lime
calcium carbonate
vinegar
impure dilute acetic acid
vitamin C
ascorbic acid
vitriol
sulfuric acid
washing soda
sodium carbonate
water glass
sodium silicate
white caustic
sodium hydroxide
white lead
basic lead carbonate
white vitriol
zinc sulfate crystals
yellow prussiate of potash
potassium ferrocyanide
yellow prussiate of soda
sodium ferrocyanide
zinc vitriol
zinc sulfate
zinc white
zinc oxide

For help in sourcing the chemicals you need give us a call on 0870 034 2055 or visit our website on the link below.
P&R Labpak Website

Ebay Shop now OPEN!!

Our ebay shop is now open for business.  We will be adding stocks over the coming weeks so please keep coming back to see what we have on offer.  If you have any particular requests for products you would like to see on the ebay shop then let us know and we’ll see what we can do.