why must the khp and the acid samples be dried?
402571
The KHP and acid samples must be dried so that their measured masses are actually proportional to the number of moles of each acid sample. If they were not dried, they'd be heavier than they should with the excess water.
768643
The recommended ways to dry NMP are to use stir over CaH2 for 12 hours, distillation (not bad as it distills at 202 ºC and does not form an azeotrope with water), store over 4 angstrom sieves.
966603
“Pallets that have been dried with heat are completely safe to burn, they will be marked H/T (heat treated not with chemicals).
829310
Unfortunately, NaOH is not a suitable primary standard. Solid NaOH is highly hygroscopic (it absorbs water from the air) and thus it cannot be accurately weighed. ... The primary standard we will use is potassium hydrogen phthalate (KC8H5O4, often abbreviated KHP).
1265555
Since mixtures can be separated into their individual constituent parts, mixtures can be tested by paper chromatography to separate and identify the combined pure substances comprising the mixture. ... Since, when tested with paper chromatography, ink separates into its constituent pure substances, ink is a mixture.
825135
['Each test uses up a piece of paper to determine a single pH value. ... ', 'Litmus paper uses a qualitative value (color) to give a general idea of pH value. ... ', 'Litmus paper contains chemicals which may leach into the sample.']
902500
Containment/Cleanup Don appropriate gloves, eye protection, lab coat, etc. Per SDS use absorbents* (e.g., “spill pillows” for solvents), or neutralizers appropriate for the material*, e.g. sodium bicarbonate for acids, citric for bases. Package and label waste. Include contaminated clothes, rags, equipment, etc.
926333
Store in a cool dry place, ideally not refrigerated.
132245
Entry-level pKa and LogP measurement. ... A pKa, the pH at which a molecule is half-ionized, is important because most biologically active compounds are ionizable. LogP, a compound's partition coefficient between an oily and aqueous phase, is used to predict absorption and is pKa-dependent.
151341
The separation principle of HPLC is based on the distribution of the analyte (sample) between a mobile phase (eluent) and a stationary phase (packing material of the column). Depending on the chemical structure of the analyte, the molecules are retarded while passing the stationary phase.
1125020
['Suspend 88.1 gm of dehydrated medium in 1 liter of distilled or deionized water.', 'Slowly bring to boiling, stirring with constant agitation until complete dissolution.', 'Do not autoclave.', 'Cool to 50°C and pour into sterile Petri plates.']
1049488
['Defining the target population.', 'Specifying the sampling frame.', 'Specifying the sampling unit.', 'Selection of the sampling method.', 'Determination of sample size.', 'Specifying the sampling plan.', 'Selecting the sample.']
339380
KHP is slightly acidic, and it is often used as a primary standard for acid-base titrations because it is solid and air-stable, making it easy to weigh accurately. ... It is also used as a primary standard for calibrating pH meters because, besides the properties just mentioned, its pH in solution is very stable.
463558
Remove the test stick from the wrapper and take off the cap. ​ Place the absorbent tip in your urine stream for 5 seconds. Or, if you prefer, dip into a urine sample collected in a clean, dry container for 5 or 20 seconds, depending on the test you're using.
1418011
A- It is important to keep the developing chamber covered with plastic wrap during the development of the chromatogram so the solvent vapor can saturate the air in the chamber, the solvent does not evaporate and the chromatogram develops properly and shows the correct cations present.
1347062
You should: collect your poo (stool) sample in a completely clean (sterile) container. store the container in a fridge in a sealed plastic bag if you can't hand it in straight away.
205174
KHP is slightly acidic, and it is often used as a primary standard for acid-base titrations because it is solid and air-stable, making it easy to weigh accurately. It is not hygroscopic.