The objective of the lab was to understand the Law of Conservation of Mass. The Law of Conservation of Mass states that matter can be changed from one form into another, mixtures can be separated or made, and pure substances can be decomposed, but the total amount of mass remains constant. For example, from our experiment in the lab, we observed mass of the mixture of aqueous Sodium Sulfide and aqueous Zinc chloride turned white color. After the filtration, and all the water was evaporated, we measured the mass very close to what we had started at the beginning. The error in mass occurred because of the remained residue (solute) in the beaker. We were unable to completely clean water, and some mass was added because we couldn’t evaporate …show more content…
(NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4H2O(g) …show more content…
A net ionic equation shows only the species that actually take part in the reaction. In solution, Na2S dissociates into Na and S2 ions and ZnCl2 dissociates into Zn2 and Cl ions. As per our lab, zinc ions (Zn 2) and sulfide ions (S2) formed an insoluble compound, zinc sulfide (ZnS), while the other product, NaCl, was soluble and remains in solution. This reaction is called a precipitation reaction. The balanced molecular equation is: Na2S(aq) + ZnCl2(aq) = ZnS(s) +2NaCl(aq). The ionic and net ionic equations are: Ionic: 2Na(aq) + S2(aq) + Zn2(aq) + 2Cl(aq) ZnS(s) +2Na(aq) + 2Cl(aq), and net ionic: Zn2(aq) + S2 (aq)+ ZnS(s). Chemical reaction occurred from the ammonium dichromate(Decomposition) was exothermic reactions. In a double displacement reaction two compounds exchange bonds or ions in order to form different compounds. An example of a double displacement reaction occurred between zinc chloride and sodium sulfide to form zinc sulfide and sodium chloride. ZnCl2(aq) + Na2S(aq)= ZnS(s) + NaCl(aq). Ionic reactions occurred between ions in aqueous solution. A reaction occurs when a pair of ions come together to produce at least one of the following: a precipitate, a gas, water, or some other non‐ionized substance. An examples of ionic reactions, if a compound is soluble in water then it should be shown as being in aqueous solution, or left as separate ions. Net ionic equations show
An error that could have been present during the lab includes not letting the zinc react completely with the chloride ions by removing the penny too early from the solution. For instance, the percent error of this lab was 45.6%, which was determined by the subtraction of the theoretical percent of Cu 2.5% and the experimental percent of Cu 3.64% and dividing by the theoretical percent of Cu 2.5%. This experiment showed how reactants react with one another in a solution to drive a chemical reaction and the products that result from the
While the solution dissolved, 50 mL of distilled water was added to a 150 mL beaker and heated on the hot plate. When the solution started to boil 2.65 grams of Na2SiO3*5H2O was added to the beaker with a stir bar and heated to a gentle boil. When both solutions began to boil, the sodium silicate solution was slowly added to the sodium aluminate. The solution was kept at 900C for 60 minutes and stirred with stir bar. After 60 minutes, the zeolite solution was cooled for 5 minutes and for the magnetized zeolite , 0.78 grams of FeCl3 and 0.39 grams of FeSO4*7H2O was added to the flask and stirred until the iron parts dissolved.
Discussion 1. Zn0 (s)+ Cu2+S6+O42-(aq) →Cu0(s) + Zn2+S6+O42-(aq) Zn0(s) → Zn2+(aq) + 2e- Cu2+(aq) + 2e- → Cu0(s) Zn0(s) + Cu2+(aq) → Zn2+(aq) + Cu0(s) Oxidant (oxidizing agent) is the element which reduces in experiment.
Conclusion: Compare Trial 1 and Trial 2. The Trial 1 change in mass are 12.5g, however Trial 2 changes in mass is 1.2g. The Trial 1 change in mass is more than Trial 2. And I think the Low of Conservation of Mass violated in the Trial 1 is can be exist. Because the Trial 1 actually the soda with vinegar have Chemical reactions occur and chemical
Lastly, the unknown compound was reacted with two different salts. For the first salt, 0.50 grams of KCl was mixed with 5 mL of water in one beaker while 0.5 grams of NaNO3 was mixed with 5 mL of water in a different beaker. Then, the NaNO3 solution was added to the KCl solution. To perform the reaction with the second salt, 0.50 grams of KCl was mixed with 5 mL of water and 1 mL of 1 M Ag(NO3)2 was added. After performing each reaction, the solution was observed to see if a reaction occurred and the pH value of the resulting solution was tested using a pH
How do you know? It is a chemical change because it turned into a new substance. In addition, Was the mixture a homogeneous or heterogeneous mixture? Explain.
For the first beaker we added 15 mL of 1M zinc sulfate into a clean medium beaker. At first we added the 15 mL of zinc sulfate into a large beaker, but when we inserted the salt bridge, we noticed that the salt bridge was not long enough to reach the 15 mL of solution in both large beakers. For the second medium beaker we added 15 mL of 1M copper sulfate. After both beakers were filled with 15 mL of the given solutions, we then placed the u-shaped salt bridge into the beaker, with one end of the salt bridge in the zinc solution and the other end in the copper solution. We had to make sure that the salt bridge was set up properly, so before inserting the salt bridge in the beakers, we added 0.2M potassium nitrate into the salt bridge, but were careful not to overflow the solution.
The equilibrium concentrations are used to calculate the concentration that all of the components of the chemical equation are at equilibrium. Using a colorimeter or spectrometer to determine the equilibrium concentration of FeSCN2+(aq) and
According to your lab instructor, unhook the spring and remove the hanging mass from the centripetal force apparatus and determine the mass Hanging by using a balance. The radial indicator at the one extreme position. Used Vernier caliper to measure the diameter of the center pole, which is on centripetal force. Three times students have to measure the length of the pole, and at the end get an average.
In this experiment, the evolution of the copper cycle was observed through a series of reactions. Four different copper compounds are formed through different reactions to inevitably lead to the recovery of Cu(s). This primary goal of this experiment was to study the Law of Conservation of Mass and perform 5 reactions on copper compounds. As Jenna Winterberg states in her book “Conservation of Mass,” the first part of this law is that mass or matter cannot be created. The second part of the law is that mass or matter cannot be destroyed .
One of the reactions you observed resulted in this product: NaCl + H2O + CO2 (g)? What well did this reaction occur in? Describe how the observations for this reaction support your answer. B BoldI ItalicsU Underline Bulleted list Numbered list Superscript Subscript70 Words A reaction I observed in number 1.)
Use the evidence provided by the tests to identify the mystery powder. The mystery powder (#5) is the baking powder. My partners and I figured this out because the physical and chemical properties of both of the substances are very similar. For example, both powders are not soluble in water, and they both turned red when they reacted with the universal indicator.
If any chemical is added or brought near another chemical, then a reaction will occur and physical and chemical changes will be seen. Procedure Procedure and Materials taken from Nelson Science Perspectives 10 pages 244 to 247 Material changes include: Glowing splint used in placed of limewater in Station 2 Magnesium
+ H2O (g) Reaction 4: when a sulphuric acid is added to the solution that contains copper (II) oxide, a double displacement reaction will occur. the copper (II) oxide will react with the sulphuric acid producing copper (II) sulfate and water. The copper and hydrogen gas replace each other. Balanced Chemical Equation: CuO (s) + H2SO4 (aq) —> CuSO4 (aq) + H2O (l) Reaction 5: when zinc is added to the copper (II) sulfate solution, a single displacement reaction will occur.
Throughout the experiment, copper was altered a total of 5 times, but after the final chemical reaction, solid, elemental copper returned. Each time the solution changed color, a precipitate formed, or when gas appeared, indicated that a chemical reaction was occurring. For the first reaction, copper was added to nitric acid, forming the aqueous copper (II) nitrate (where the copper went), along with liquid water, and