Limiting reactants and excess reactants
In the first experiment we noticed how Phenolphthalein, thiosulfate and copper (II) sulfate changed their physical properties once mixed with NaOH, Iodine and Ammonia
I. INTRODUCTION
A chemical reaction is a change that takes place when two or more substances (reactants) interact to form new substances (products).
In a chemical reaction, not all reactants are necessarily consumed.
One of the reactants may be in excess and the other may be limited.
The reactant that is completely consumed is called limiting reactant, whereas unreacted reactants are called excess reactants.
Amounts of substances produced are called yields. The amounts calculated according to stoichiometry are called theoretical yields whereas the actual amounts are called actual yields. The actual yields are often expressed in percentage, and they are often called percent yields. In this experiment we combined sulfuric acid and aqueous barium chloride to produce a precipitate, barium sulfate and hydrochloric acid. The precipitation was isolated by filtration and theoretical yield was calculated. We predicted the limiting reactant and verified our hypothesis in the lab.
II. RESULT ANALYSIS
GRAPH
II. DISCUSSION
In this experiment we combined sulfuric acid and aquenous barium chloride to produce a precipitate, barium sulfate, and hydrochloric acid. Our assigned volumes of 0.20 M BaCl were 5mL and 30mL.
H SO + BaCl BaSO + 2HCl
After finishing the experiment we calculate the mass of BaSO that we isolated. The results of the two trials were:
0.7g when we used 30 mL of BaCl and
0.017g when we used 5 mL of BaCl.
1. We calculated the theoretical yield of BaSO using our assigned volume. We know that:
Molarity= # of moles/ # of liters, so:
Trial 1.
To find the number of moles we use the molarity formula:
30mL= 0.03L
0.2M = #of moles/ 0.03L = 0.006 moles of BaCl
We know from the chemical formula that there is a 1/1 mole ratio between BaCl and BaSO, and that AW of 1 mol of BaSO = 233.404, so we transform moles to grams:
0.006 x (233.404g) =1.400g BaSO
Trial 2.
To find the no. of moles we used the molarity formula:
5.0 mL = 0.005L
0.2M = # of moles / 0.005 = 0.001 moles of BaCl
AW of 1 mole of BaSO = 233.404g, so we transform moles to grams:
0.001 x (233.404g) = 0.233g BaSO
2. After determining the theoretical yield we calculated the percent yield of BaSO:
Trial 1.
The actual mass of BaSO isolated in our experiment was 0.
Baking Soda and Vinegar: Limiting Reactant Lab Background The limiting reactant of a chemical reaction is the substance that places an upper bound on the amount of product that the reaction can produce. The limiting reactant places this upper bound because the reaction must stop once all of the limiting reactant is consumed. If the relative amount of reactants is altered, then the limiting reactant may change accordingly.
2-ethyl-1,3-hexanediol. The molecular weight of this compound is 146.2g/mol. It is converted into 2-ethyl-1-hydroxyhexan-3-one. This compounds molecular weight is 144.2g/mol. This gives a theoretical yield of .63 grams. My actual yield was .42 grams. Therefore, my percent yield was 67%. This was one of my highest yields yet. I felt that this was a good yield because part of this experiment is an equilibrium reaction. Hypochlorite must be used in excess to push the reaction to the right. Also, there were better ways to do this experiment where higher yields could have been produced. For example PCC could have been used. However, because of its toxic properties, its use is restricted. The purpose of this experiment was to determine which of the 3 compounds was formed from the starting material. The third compound was the oxidation of both alcohols. This could not have been my product because of the results of my IR. I had a broad large absorption is the range of 3200 to 3500 wavenumbers. This indicates the presence of an alcohol. If my compound had been fully oxidized then there would be no such alcohol present. Also, because of my IR, I know that my compound was one of the other 2 compounds because of the strong sharp absorption at 1705 wavenumbers. This indicates the presence of a carbonyl. Also, my 2,4-DNP test was positive. Therefore I had to prove which of the two compounds my final product was. The first was the oxidation of the primary alcohol, forming an aldehyde and a secondary alcohol. This could not have been my product because the Tollen’s test. My test was negative indicating no such aldehyde. Also, the textbook states that aldehydes show 2 characteristic absorption’s in the range of 2720-2820 wavenumbers. No such absorption’s were present in my sample. Therefore my final product was the oxidation of the secondary alcohol. My final product had a primary alcohol and a secondary ketone
The question I was trying to answer is Which balanced chemical equation best represents the thermal decomposition of sodium bicarbonate. Using that question to guide us we were trying to determine which of the four chemical equations show how atoms are rearranged during thermal decomposition. We concluded it was the second chemical equation, we know that because:
How am I going to make it a fair test I will use a clean flask for
The mean for the temperatures is 0.116 and the solvents is 20. We predicted the 37 Celsius would be the most absorbed, but it was the -20 Celsius which can be seen in the graph above.
It has a molar volume of 9.38 ×10-6 m3/mol. Molybdenum has an atomic weight of 95.94 amu. Its atomic number is 42. The atomic radius is 145 pm and the covalent radius is 145 pm also. Its electron configuration is [Kr]4d^5 5s^1.
* Note the mass down in the table at the end of the first page.
It is important however to note that the NH4 and K ions are still in
-443.08 x (100.1 / 2.51) = -17670.2 J.mol. 1. H = -17.67 kJ.mol. 1.
The % composition by mass of oxygen in Potassium Chlorate was found to be 43.4%.
From looking at the results I can conclude that when the pH was 3 and
A. A. The "Bisphenol A" National Geographic, 18 Sept. 2008. Web. The Web. The Web. 8 Mar. 2014.
Our world is too small for our ever rapidly growing population. One day resources will run dry and vanish, which will bring death and loss to all nations on this planet. Many researchers and scientists have confirmed that the population will reach 10 billion by the end of the century and will continue to stream upward. There are many different ways in trying to decrease population to contain global warming and assist our environmental changes. The only way to steadily succeeding, families must be the regulators of their fertility and future. Environmentalism can head in a negative direction, which may result in population control and even anti-immigrant policies. Can the developing effort of ‘population integrity’ protect our world while recognizing birth moralities?