Answer: When zinc is added to copper sulphate (CUSO4) solution due to more reactivity of zinc, cooper is replaced by the zinc and forms zinc sulphate. During the process, the colour of the solution changes from blue to colourless.

What experimental result would be evidence that a chemical reaction took place when the solutions were combined? Bubbles formed when the two solutions were combined. The total volume of the mixture is close to the sum of the initial volumes. The resulting solution is colorless.

How does the amount of HC2H3O2(aq) in the flask after the addition of 5.0mL of NaOH(aq) compare to the amount of HC2H3O2(aq) in the flask after the addition of 1.0mL of NaOH(aq), and what is the reason for this result? it is less because more HC2H3O2(aq) reacted with the base.

Which of the following best describes the process represented above that takes place when NH3 is added to water? It is an acid-base reaction in which a proton is exchanged from H2O to NH3. When the reaction represented above proceeds, heat is produced.

When water is added to a mixture of Na2O2(s) and S(s), a redox reaction occurs, as represented by the equation below. Two trials are run, using excess water. In the first trial, 7.8 g of Na2O2(s) (molar mass 78 g/mol) is mixed with 3.2 g of S(s). In the second trial, 7.8 g of Na2O2(s) is mixed with 6.4 g of S(s).

The third law of thermodynamics establishes the zero for entropy as that of a perfect, pure crystalline solid at 0 K. With only one possible microstate, the entropy is zero.

Which of the following best describes what happens to the pH of the H2O2 solution as the titration proceeds? As H+ ions are consumed, the solution becomes less acidic and the pH increases.

When a buret is rinsed before a titration, which of the techniques below is the best procedure? (A) Rinse the buret one time with some of the titrant solution. Rinse the buret two times: once with some of the titrant solution, then-once with distilled water.

If droplets remain on the inside surface, wash the buret with detergent solution, rinse several times with tap water, then rinse three times with distilled water. Rinse with solution: After draining the final distilled water rinse, close the stopcock and add about 5 mL of the solution to be dispensed from the buret.

Due to the fact, that all burettes are made of glass, it can absorb and remain water on the surface, because of the polarity of the glass and intermolecular forces. Thus, you have to rinse the burette with a solution which must be filled in it, because distilled water change the concentration of the initial solution.

This is a waste of time, as all volumes delivered by a buret are determined from the difference between initial and final readings. Close the stopcock, tap the buret sides gently, and allow the liquid to stand for a few minutes to clear gas bubbles dissolved in the liquid.

Always make sure the burette is clamped in a perfectly vertical position before taking any readings. When adding solutions to the buret, make sure the stopcock is closed (horizontal position).

Burette clamp is a scientific equipment which used specifically to hold and secure a burette on a stand, so that a burette is fixed and more convenient for the experiment. Burette clamps can be made with many materials such as plastic and cast iron.

So that drops of solution from the funnel do not drip into the burette, affecting the volume of solution. Why is it important to clamp the burette vertically? To allow the liquid level to be read correctly. Why is it important to have the part below the burette tap full?

Burets are used primarily for titration, to deliver one reactant until the precise end point of the reaction is reached. To fill a buret, close the stopcock at the bottom and use a funnel. You may need to lift up on the funnel slightly, to allow the solution to flow in freely.

The burette tube carries graduated marks from which the dispensed volume of the liquid can be determined. Compared to a volumetric pipette, a burette has similar precision if used to its full capacity, but as it is usually used to deliver less than its full capacity, a burette is slightly less precise than a pipette.

While burette is used to deliver a chemical solution with a known concentration into a flask, pipette is used to measure the quantity of the analyte- the chemical substrate whose concentration is to be determined.

First it is rinsed internally with deionised water (3 small rinses). Then it must be rinsed 3 times with the solution to be pipetted, as follows: Transfer about 20mL of deionised water into a clean dry beaker and, using a pipette filler, draw a small amount (5mL) of water into the pipette.

Micropipettes use a disposable pipette tip to aspirate liquid, note that the tip is the only part of the pipette that makes contact with the solution. A new tip is utilized for every sample in order to prevent cross contamination.

Numbers on the micropipette (typically black-black-red) are read as XX. X µl. The change in color indicates the position of the decimal point. P200: Maximum volume 200 µl.

Calculate the accuracy of the pipette.

1. If the pipette is properly calibrated, the calculated value should be very close to the actual value you set on the pipette.
2. For example: A = 100 x Vavg/V0 = 100 x 10.019/10 = 100 x 1.0019 = 100.19%
3. This particular pipette is properly calibrated.

volumetric pipette

A typical plastic pipette works as a vacuum, with fluid drawn in and out of the tool by squeezing the ‘bulb’. Electronic pipettes are recognised as being even more accurate than traditional pipettes.

You Use an Air Displacement Pipette, Most Likely Temperature and pressure affect the volume of the air cushion, which affects pipetting accuracy. Also, volatile solvents can evaporate into the air cushion, which leads to an inaccurate and lower dispensed volume than that displayed on the pipette.