Stoichiometry Lab Report

The topic of research is, “how fast does an Alka-Seltzer tablet make gas?”. In the experiment, the scientists will be measuring the chemical reaction rates that occur, when 1 Alka-Seltzer tablet is placed in a specific temperature of water. The independent variable during the experiment will be the temperature of the water (degrees Celsius). The dependent variable during the experiment will be, the rate in which gas is produced (in seconds). The constants of the experiment, will be the amount of water used and the Alka Selter compound. The control in the experiment is water. Units used while timing the productivity of gas from an Alka-Seltzer tablet in different temperatures is, seconds.

Alka-Seltzer has been on the market since 1931 and has helped to relieve indigestion and upset stomach. The tablets began to fizz and bubble when dropped into water. “The fizziness happens when baking soda (sodium bicarbonate) and citric acid react chemically in water. They yield sodium citrate, water and carbon dioxide gas, which causes bubbles.” Based on this information, we will measure the reaction time of AlKa- Seltzer dissolved in 200 ml of water at 3 different tempertures in the first portion of this experiment. In the second portion of this experiment we will keep the temperature constant and divide the ½ tablet of Alka- Seltzer into 2 pieces ,3 pieces and an unbroken ½ tablet. It is my belief that Alka-Seltzer

In this lab, you will investigate the percent composition by mass of CO2 in Alka-Seltzer® tablets. In addition, you will find out how much CO2 is released into the atmosphere as 2 Alka-Seltzer® tablets chemically react in vinegar.

Stoichiometry is a method used in chemistry that involves using relationships between reactants and products in a chemical reaction, to determine a desired quantitative data. The purpose of the lab was to devise a method to determine the percent composition of NaHCO3 in an unknown mixture of compounds NaHCO3 and Na2CO. Heating the mixture of these two compounds will cause a decomposition reaction. Solid NaHCO3 chemically decomposes into gaseous carbon dioxide and water, via the following reaction: 2NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g). The decomposition reaction was performed in a crucible and heated with a Bunsen burner. The study of Green Chemistry emphasizes the reduction of hazards to human health and the larger environment, as well as

All matter is made of particles called atoms. An atom is smallest unit of matter. A matter can be solid, liquid or gas. When a group of atoms bond together this makes a molecule. The molecule is the base of chemical compounds that is involved in chemical reactions. A mixture of elements is what is known as compounds. Chemical reactions occur when particles react with each other and atoms in molecules get rearranged. Reactions happen either rapidly or slowly. The speed of a reaction is known as the rate of the reaction. This speed of chemical reaction depends on many factors such as temperature, particle size of reactants, and the intensity of reactants. A reactant is the substance that is used up in a chemical reaction to give product, which is the substance that is made at the end of the reaction. Besides, the energy of the molecules that determines how fast molecules are moving is known as temperature. Therefore, the rate of the reaction that happens between molecules is affected by the size of the reactant.

In the experiment, the problem was the contaminants that were affecting the quality of the water samples. To fix this issue, three scientists had to determine the contaminants that were present in the samples. One sample was from the school sink and the second sample was from an unknown source. The scientists conducted many tests to figure out what pollutants were present in the water. In the experiment they used probes to test for pH, dissolved oxygen, total dissolved solids, conductivity, and turbidity. The probes hook up to the computer and collected the averages for each test. They collected this data and used it for later evaluation of the contaminates. They also tested for iron, copper, and chlorine with different tablets.

For this lab the knowledge to tell the difference between a chemical and physical changes was needed. To tell this the knowledge of the five signs of a chemical change was needed. These five signs are color change, odor change, production of bubbles/gas, production of heat/light, and the production of precipitate. Also prior to the lab one question was provided that needed to be answered. This question was what chemical must be present for a color change. The hypothesis that was provided to this question was If Phenol Red is add with the other chemicals then a color change will occur.

The possibilities for the identity of the metal include copper and iron (1). The possible charges for copper are 1+ and 2+ (2). The possible charged of iron are 2+ and 3+ (2). By using stoichiometry, it can be concluded that there are only four possible equations:

The lab started off by measuring critical materials for the lab: the mass of an an empty 100 mL beaker, mass of beaker and copper chloride together(52.30 g), and the mass of three iron nails(2.73 g). The goal of this experiment is to determine the number of moles of copper and iron that would be produced in the reaction of iron and copper(II) chloride, the ratio of moles of iron to moles of copper, and the percent yield of copper produced. 2.00 grams of copper(II) chloride was added in the beaker to mix with 15 mL of distilled water. Then, three dry nails are placed in the copper(II) chloride solution for approximately 25 minutes. The three nails have to be scraped clean by sandpaper to make the surface of the nail shiny; if the nails are not clean, then some unknown substances might accidentally mix into the reaction and cause variations of the result. This is important because the correct reaction would only appear if the right elements are mixed together, the unknown substances on the iron nails can cause a different reaction to happen that is not expected.

Sunlight is converted into ATP (free energy containing molecule) and NADPH (high energy electron carrying molecule)

Background: In this unit, we began to learn about stoichiometry; where we measure and compare how many chemicals we have, before and after the reaction. Balancing moles and balancing equations are large components in setting up a problem. Another component that we have studied is the yield of reaction (how much product you get). When doing a stoich problem the amount of product you get is a theoretical yield. Your actual yield is the measurement you get using a balance.

In our lab we were asked Which Balanced Chemical Equation Best Represents the Thermal Decomposition of Sodium Bicarbonate. Sodium Bicarbonate is a chemical compound with the formula NaHCO3, also known as baking soda. In the process to answer our guiding question we have to determine how atoms are rearranged during a chemical reaction. That is where stoichiometry comes along, which is the quantitative relationships or ratios between two or more substances undergoing a physical or chemical change in a balanced equation. It identifies the mole ratio between reactants and products. To understand stoichiometry you have to understand the products and reactants, which involves how to solve balanced reactions. This allows chemists to determine how many moles of a product will be produced from a specific number of moles of a recant or how many moles of reactant are needed to produce a specific amount of a product.

When testing the effects of hydrochloric acid on different solutions data was collected that showed that liver cells have a buffer and celery do not which supports the original hypothesis of liver cells containing a buffer. A buffer is a solution that resists change in pH when acid is added to it. A buffer will release more hydroxide ions when there is acid added. Each solution in the lab was tested first at its original pH and then after five drops each was tested until there were 30 drops added in. When tested in the lab two controls were used one positive for having a buffer (alka seltzer) and one negative (water). Alka seltzer started with a pH of 6.5 and barely fluctuated with each new drops added it finished with a pH of 6.47 showing

The guiding question of this ADI lab was, “Which balanced equation best represents the thermal decomposition of sodium bicarbonate?” The goal of this lab was to use our knowledge of stoichiometry with the mole ratio to identify the correct chemical equation for the decomposition of sodium bicarbonate. Information that was given going into this investigation was the definition of the law of conservation of mass and the atomic theory which states that no atoms can be created nor destroyed during a chemical reaction. Also the mole ratio which is used to determine how much of a product will be produced in a chemical reaction using the given chemical equation. To conduct the lab, information regarding

(0.0035 moles of CaCl2) x (1 mole Ca(OH)2/ 1 mole of CaCl2) = 0.004 moles of Ca(OH)2