Jacob Dyer
Mrs. Nakai
3A
Double Replacement Reactions Lab
Aim/Problem
The aim of this experiment is to prove if double replacement reactions
happen based on finding evidence supporting it. What reaction will
happen in the mixing of solutions that will prove double replacement is
happening? My independent variables are the different solutions we
will mix and the dependent variable is the result of this mixture of
solutions.
Hypothesis
If double replacement does happen, then it will be shown if a
precipitate formed, there is a release of gas or permanent color
change because when double replacement reaction happens there will
be a chemical reaction from the different elements in the combine with
other elements in the other compound.
Experimental Method:
Our experimental method is to find evidence of double replacement
and if it happens. We are going to mix solutions from Group A to
solutions in Group B and record the visible results (looking for
precipitates being formed, gases being released, and permanent color
changes). Safety equipment that was used were gloves, an apron and
safety goggles. A table was produced to put in evidence of reactions
and observations of reactions. The formula for double replacement is
AB + CD  AD + CB.
Jacob Dyer
Mrs. Nakai
3A
Note: We did not balance the double replacement equation for each of
the combinations. Also we did not write out the equation for each of
the combinations that showed any type of reactivity. Instead, we
chose examples of each type of reaction (e.g. forms precipitate or
color change) and we wrote out the equations for them.
Other Materials: goggles, apron, and a computer for recording
observations and taking pictures.
Data Processing
Formulas for Different Reactions
Note: Formula for double replacement is AB + CD  AD + CB.
Color Change
Jacob Dyer
Mrs. Nakai
3A
Copper (II) Nitrate (Cu(NO3)2) with Sodium
Chromate (Na2CrO4)
Cu(NO3)2 + Na2CrO4  CuCrO4 + NO3Na2
Copper (II) Nitrate (Cu(NO3)2) with Sodium
Thiocyanate (NaSCN)
Cu(NO3)2 + NaSCN  CuSCN + NO3Na
Nickel (II) Nitrate (Ni(NO3)2) with Sodium
Carbonate (Na2Co3)
Ni(NO3)2 + Na2Co3  NiCo3 + Na2NO3
Forms Precipitate
Copper (II) Nitrate (Cu(NO3)2) with Ammonium
Hydroxide (NH4OH)
Cu(NO3)2 + NH4OH  CuOH + NO3NH4
Copper (II) Nitrate (Cu(NO3)2) with Sodium
Chromate (Na2CrO4)
Cu(NO3)2 + Na2CrO4  CuCrO4 +NO3Na2
Copper (II) Nitrate (Cu(NO3)2) with Sodium Iodide
(NaI)
Cu(NO3)2 + NaI  CuI + NO3Na
Forms Gas
Sodium Carbonate (Na2Co3) with Nitric Acid (HNO3)
Na2Co3 + HNO3  Na2NO3 + Co3H
Note: The picture was not high enough quality to see the bubbles
formed by the release of gas in the reaction.
Jacob Dyer
Mrs. Nakai
3A
Evaluation
From the data we gathered from mixing different compounds, my
hypothesis that if double replacement does happen, then it will be
shown if a precipitate formed, there is a release of gas or permanent
color change was proven correct. There were many examples of a
precipitate being formed and of permanent color changes.
An example of a precipitate being formed was shown in the mixture of
the compounds Copper (II) Nitrate (Cu(NO3)2) and Ammonium
Hydroxide (NH4OH) which when mixed created a blue precipitate. The
elements switched the elements that they were bonded to according to
the AB + CD  AD + CB rule which made the equation of this chemical
reaction Cu(NO3)2 + NH4OH  CuOH + NO3NH4.
An example of a permanent color change was shown in the mixture of
Lead (II) Nitrate (Pb(NO3)2 and Sodium Iodide (NaI) made a bright
yellow color change. The formula for this reaction is: Pb(NO3)2 + NaI
 PbI + NO3Na. Even though there were many examples of double
replacement happening through precipitates being formed an
permanent color changes, there was only one example of a release of
gas (with a mix of Nitric Acid (HNO3) and Sodium Carbonate (Na2Co3)).
This may have been because Sodium Carbonate is a very reactive
compound as it was the only compound to have a reaction to every
single one of the other compounds.
In a double replacement reaction, a metal replaces a metal in a
compound and a non-metal replaces a non-metal in a compound,
which causes a chemical reaction such as precipitates being formed,
gases being formed, and a permanent color change.
Even though the experiment we did showed results supporting our
hypothesis, there were many things that could have gone wrong and
mistakes we could have made. One procedural error that happened is
that for some chemical reactions we either forgot to take a picture for
it or forgot to label the picture as the substances that were mixed.
This decreased the amount of evidence we had to support our
hypothesis. Another error that may have taken place was measuring
the amount of each compound to put into the micro plate. The
experiment specified having four drops from a pipette or the bottle
with the substance however, sometimes it was hard to control the four
drops coming out and make sure the substances were staying in their
holes because they were so small. A third error we might have made
was that we may have not waited long enough and observed closely
enough for a reaction because some reaction may have happened over
time and others are very hard to see such as changes in heat which
Jacob Dyer
Mrs. Nakai
3A
can only be felt.
If I were to repeat this experiment, there would be a few things I
would do differently. First of all, I would give the reactants more time,
so that I can see if there are reactions that occur over a period of
time. I would also try to measure out the substances before putting
them into the micro plate to get more accurate observations. A third
improvement I would make would be to instead of using my
computer’s camera for pictures, I would use a real camera to take
pictures with more detail and higher quality.