Suppose that you start with .303g of copper wire and faithfully follow the procedure. at the end you find that the copper dust weighs .309g. base on your understanding of the experimental procedure, offer at least two rational explanations for this apparent violation of the law of conservation of mass.
the experiment is a sequence of Chemical Reactions. Procedure part A preparation fo copper (II) Hydroxide-get a solution of copper(II)nitrate. measure 25ml of solution. to blue solution add 2mL of concertarted NaOH while stirring. Let mixture settle and use litmus paper to test acidity. add addition 10 drop portions of 6M NaOH while stirring until basic. Add 30 mL of water to beaker stir well and allow misture to settle. pour off major part of clear, colorless liquid into a beaker. Save precipitate and residual liquid for part B. Part B-Add dilute (3M) H2SO4 with constant stirring to beaker containing supsension of Cu(OH)2. save color solution of CuSO4 for part C. Part C-add 6M NaOH with constant stirring to colored solution from B until a small amount of blue is visable. Add about 10mL of Na3PO4 solution stirring thoroughly. test with litmus paper. Part D-Add 15mL of 6M HCl to solution from part C. When precipitate is gone filter solution using long stemmed glass funnel and filter paper. Wash filter paper with 20 drops of de-ionized water through filter into beaker containing CuCl2 solution. Part E-to solution CuCl2 add 4 or 5 pieces of magnsium turning and keep them submerged with tip of stirring rod. Add minumum possible quality of concentrated (12M) HCl, to destro excess magnesium. Allow copper to settle. Discard major part of liquid and wash solid copper dust 4 times with 15mL portions of de-ionized water. drain as much water as possible leaving behind copper. place beaker on hot plate and heat until completely dry. after cooled weigh to nearest .001g and record mass. transfer all dried copper onto weighing paper.
Mass of beaker with copper=57.758g
Mass of copper=.243g
.157M X.025L=.003925mols
.003925molsX (1 molCu/i mol Cu(NO3)2) X (63.55g Cu/1 mol Cu)=.25
.243/.25=97.2 % yield
There are a few possible rational explanations for the apparent violation of the law of conservation of mass in this experimental procedure:
1. Experimental Error: It is possible that there were errors in the experimental procedure or measurements. Small errors in weighing the initial copper wire or collecting the copper dust could result in a discrepancy in the mass measurements.
2. Contamination or Loss: During the process of converting the copper wire into copper dust, it is possible that some dust particles were lost to the surroundings or there could have been contamination from other sources. These factors could result in a higher measured mass for the copper dust.
It is important to note that the law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction or a physical change. However, errors, contaminations, or losses can occur during experimental procedures, leading to apparent violations of this law in individual measurements.
To offer rational explanations for the apparent violation of the law of conservation of mass in this experiment, we need to consider the factors that could contribute to the increased weight of the copper dust compared to the initial copper wire.
1. Oxidation Reaction: Copper is known to readily react with oxygen in the air, forming copper oxide. If the copper wire was exposed to oxygen during the experiment, it is likely that a chemical reaction occurred, leading to the formation of copper oxide and increasing the overall mass. This increase in mass would account for the observed weight gain in the copper dust.
2. Contamination: It is possible that the copper wire or the equipment used in the experiment was contaminated with impurities or other substances. If these impurities were present during the measurement of the copper dust's weight, they could have contributed to the increased mass. This could be due to residues from previous experiments, dust particles, or even small amounts of other metals.
To confirm these explanations, it is essential to follow a set of steps to investigate further:
1. Repeat the experiment: Perform the same procedure using another sample of copper wire and make sure to properly control the conditions to eliminate any potential contamination, such as using clean equipment.
2. Control experiment: Conduct a control experiment where the procedure is followed, but without exposing the copper wire to any possible oxidizing agents, such as oxygen or other reactive gases, to determine if oxidation is indeed responsible for the increased mass.
3. Chemical analysis: Carry out a chemical analysis of both the copper wire and the copper dust to identify the presence of any other substances or compounds that could explain the weight difference. This will help determine if contamination is the cause.
By conducting these further investigations, it will be possible to determine the actual cause of the observed mass increase and confirm or reject the explanations proposed.
Missy--
This is the first of three posts I've read today by you, all dealing with Cu and/or Cu3(PO4)2. Yet you give no clue as to what experiment you are doing, what has been added, or any of the details. If you want help here you must provide more data than that. I will ignore the other two posts (later than this one).