#### Can one determine the coefficients of a balanced chemical equation by having the mass of a reagent, the mass of the dry product and by using stoichiometry?

Purpose Can one determine the coefficients of a balanced chemical equation by having the mass of a reagent, the mass of the dry product and by using stoichiometry? Hypothesis If the mass of the aluminum and the mass of the dry product, copper, is known then the balanced chemical equation can be derived by converting the masses to moles by dividing by the empirical molar masses of the elements, and then one can do a mole to mole ratio between this product and the reactant to make a balanced chemical equation. In a balanced chemical equation the coefficients of the chemical equation are indicative of the ratio of moles of the reactants and the products in a reaction. Since molar mass is also the mass per mole of substance and one knows the mass, then if one divides the mass determined from the experiment by the molar masses of each element then logically one will get the number of moles of the substance. From there a mole to mole ratio can be done between the product and the reactant and since a chemical equation can not have a fraction as a coefficient, then the coefficients can be multiplied on both sides by a number that will get a whole number for both elements. Since the law of conservation of mass states that anything that any quantity of substance that is put into the equation must result in the same quantity coming out of it and vice versa. This means that the very

• Word count: 3084
• Level: International Baccalaureate
• Subject: Chemistry

#### Reaction Rate

Science Reaction Rate Between an Acid and Metal Investigation PROBLEM/RESEARCH QUESTION In this investigation, a controlled experiment will be conducted to determine whether the varying concentration of an acid alters its reaction rate with a metal substance and if so, what is the resultant relationship between the rate of reaction and the concentration of the acid. In particular, we will be reacting Sulfuric acid (H2SO4) with Magnesium metal (Mg) and collect data based on the resultant hydrogen gas produced by the reaction. Word Equation: Magnesium + Sulfuric Acid → Hydrogen gas + Magnesium Sulfate Balanced Equation: Mg (S) + H2SO4 (aq) → MgSo4 (aq) + H2 (g) Research will be formulated by conducting a controlled experiment in which we will react 0.05g of Magnesium metal ribbons (Mg) with 10mL of four different H2SO4 (Sulfuric Acid) solutions varying in concentration and determine the time it takes for the reaction to produce 20mL of Hydrogen gas with each varying concentration. HYPOTHESIS I hypothesise that as the concentration of the H2SO4 solution increases/strengthens (measured in molarity mass), it will correspond to an increased/quicker rate of reaction with Mg metal. Hence, I also hypothesise that - based on the above premise- the 2M solution of H2SO4 would be the quickest to produce 20mL of H2 gas when reacted with magnesium, as it is the strongest of

• Word count: 3043
• Level: International Baccalaureate
• Subject: Chemistry

#### To determine the molecular mass of an unknown alkali metal carbonate, X2CO3.

Candidate Name: Candidate Number: Page | International Baccalaureate Diploma Program (IBDP) Session: May 2015 Chemistry HL Lab Report Lab Report Title: To determine the molecular mass of an unknown alkali metal carbonate, X2CO3. Criteria Assessed: * Data Collection and Processing (DCP) * Conclusion and Evaluation (CE) Candidate Name: Candidate Number: International School, Singapore AIM: To determine the molecular mass of an unknown alkali metal carbonate X2CO3 using titration. INTRODUCTION: Since substance Z is an alkali metal carbonate, it can safely be hypothesized that the compound is most likely to be the carbonate of Lithium, Sodium or Potassium since these are the only three alkali metal carbonates which are stable and safe to use in a school laboratory. Alkali metal carbonates are basic in nature and dissolve in water hence forming basic solutions. These basic solutions can readily react with strong acids such as HCl to form a salt and water. Therefore, in order to determine the molecular mass of substance Z, its ability to form alkali solutions was exploited and hence, aqueous samples of substance Z was titrated against 0.1 molarity solutions of HCl. Substance Z reacts with HCl according to the following balanced chemical equation: X2CO3 (aq.) + 2HCl (aq.) → 2XCl (aq.) + CO2 (g) + H2O (l) VARIABLES: Independent

• Word count: 3039
• Level: International Baccalaureate
• Subject: Chemistry

#### Strong and Weak Acids And Bases

Strong and Weak Acids and Bases Khan Salinder Purpose In this lab, a comparison will be made of the properties of strong and weak acids, as well as properties of dilutions of strong acids. Results & Analysis Experiment #1- Measurement of pH Values Calculations for Theoretical Values of pH Hydrochloric Acid 0.1M HCL HCl --> H+ + Cl- 0.1M HCl = 0.1M [H+] pH= -log[H+] pH= 1.0 0.01M HCl HCl --> H+ + Cl- 0.01M HCl = 0.01M [H+] pH= -log[H+] pH= 2.0 Ethanoic Acid 0.1M CH3COOH CH3COOH ? H+ + CH3COO- Ka =1.8x10-5 Ka = [H+][CH3COO] / CH3COOH] [ ] CH3COOH --> H+ + CH3COO- I C E .8x10-5 = [x][x] / [0.1] x2= 0.0000018 x = 0.0013 = [H+] pH= -log0.0013 pH= 2.9 0.01M CH3COOH CH3COOH ? H+ + CH3COO- Ka =1.8x10-5 Ka = [H+][CH3COO] / CH3COOH] [ ] CH3COOH --> H+ + CH3COO- I C E .8x10-5 = [x][x] / [0.01] x2= 0.00000017 x = 0.00041 = [H+] pH= -log0.00041 pH= 3.4 Sodium Hydroxide 0.1M NaOH NaOH --> Na+ + OH- 0.1M NaOH = 0.1M [OH-] pOH= -log[OH-] pOH=1 pH=14-1=13 pH= 13.0 0.01M NaOH NaOH --> Na+ + OH- 0.01M NaOH = 0.01M [OH-] pOH= -log[OH-] pOH=2 pH=14-2=12 pH= 12.0 0.001M NaOH NaOH --> Na+ + OH- 0.001M NaOH = 0.001M [OH-] pOH= -log[OH-] pOH=3 pH=14-3=11 pH= 11.0 Table 1- Experimental ph Values pH Value from pH paper ± 0.5 Observation of ph Paper pH Value from pH meter ± 0.05 0.1 M

• Word count: 2998
• Level: International Baccalaureate
• Subject: Chemistry

#### In our research project, we will try to compare the qualitative contents of some energy drinks. These drinks will vary from international drinks to simple local energy drinks. To differentiate energy drinks form other drinks, such drinks can be compared t

Chemistry Background Information: When a person is exercising, or undergoing some sort of a strenuous activity, it has often been observed that they drink a lot of drinks. This maybe in the form of water, energy drinks, juice or it may even be carbonated sodas. Why is this so?? What Benefits do athletes get from drinking energy drinks?? How does fitness relate to energy drinks?? This answer lies in the basic chemical structure of energy drinks. These drinks consumed during exercising are much more complex than what they look like. They comprise of some vital nutrients which give the respective drinkers quick energy. Energy Drinks Energy drinks are drinks designed to increase stamina and improve physical performance. Some energy drinks are designed especially for elite athletes, but most are produced and marketed for the general community. The main ingredients in energy drinks are caffeine, taurine and glucuronolactone. Some new drinks on the market also contain opium poppy seed extract or ephedrine. Details of the ingredients present in some energy drinks: Chlorine Ions pH Glucose is the body's preferred fuel. Energy drinks contain a ton of sugar which means, they contain a lot of energy. It's a carbohydrate, and a lot of exercise regiments suggest a good dose of carbohydrates for workouts lasting more than an hour. However, to much sugar intake has been proved

• Word count: 2943
• Level: International Baccalaureate
• Subject: Chemistry

#### Analysis of the Standard Enthalpy of Combustion for Alcohols

Investigate an Aspect of Organic Chemistry Investigation of the standard enthalpy change of combustion for alcohols Sarah van der Post HL Chemistry IB Internal 24 – 6 - 2012 Design Aim: To investigate the standard enthalpy change of combustion for 5 consecutive alcohols in the alcohol homologous series, methanol, ethanol, propan-1-ol, butan-1-ol and pentan-1-ol, by using a calorimetric method to calculate the heat gained by the 100cm3 water in the experiment, and thus the heat lost by the alcohol lamp at standard temperature and pressure (298 K and 101.3 kPa). Background Knowledge: Alcohols are organic compounds containing Oxygen, Hydrogen and Carbon. The alcohols are a homologous series containing the functional –OH group. As we move down the homologous series of alcohols, the number of Carbon atoms increase. Each alcohol molecule differs by –CH2; a single Carbon atom and two Hydrogen atoms. Combustion is the oxidation of carbon compounds by oxygen in air to form CO2 and H2O. Combustion produces heat as well as carbon dioxide and water. The enthalpy change of combustion is the enthalpy change that occurs when 1 mole of a fuel is burned completely in oxygen. When alcohol undergoes complete combustion it produces carbon dioxide and water as products, and energy is released. The standard enthalpy of combustion of an alcohol (∆H°comb) is the enthalpy

• Word count: 2893
• Level: International Baccalaureate
• Subject: Chemistry

#### Chemistry extended essay - investigate the effect of 2-bromo-2-methyl propane concentration and temperature of the system on the rate of reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcohol

Chemistry Extended Essay To investigate the effect of 2-bromo-2-methyl propane concentration and temperature of the system on the rate of reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcohol Done by: Habib Iscandar Hinn Friend's Boy's School June 22, 2007 To investigate the effect of 2-bromo-2-methyl propane concentration and temperature of the system on the rate of reaction of solvolysis of 2-bromo-2-methyl propane in 90% ethyl alcohol Introduction: The major product of the solvolysis of t -butyl chloride in 70 % water - 30 % acetone is t-butyl alcohol, with a small amount of isobutylene being formed as a by product And this is with accordance of first order kinetic and suggests a two step mechanism in which the rate determining step consists of the ionization of t-butyl chloride, and in this mechanism a carbonium ion is formed as inter- mediate and this bonds immediately to near by nucleophile (in this case nucleophile is a neutral molecule) the initial product is t-butyl carbonium ion. "Note1: if the nucleophile is neutral the product will be charged since the leaving group takes both bonding electrons away with it" So chemists have proposed to general types of mechanism: - Nucleophilic substitution Sn1 The ionization step in a Sn1 reaction is endothermic and much slower than the exothermic neutralization of carbonium ion by a

• Word count: 2855
• Level: International Baccalaureate
• Subject: Chemistry

#### Dissolved Oxygen in water

Chemistry Coursework BY WASIM KHOURI Y12 SL CHEMISTRY Contents Design 3 Data Collection and Processing 6 Conclusion and Evaluation 9 Design Research Question: How does the dissolved oxygen content vary at different stages of the sewage treatment plant in Istra? Hypothesis: Dissolved oxygen in water is very important for many plants and animals so that they can undergo aerobic respiration. At a pressure of one atm and a temperature of 20 °C the maximum solubility in water is only about (9 mg l-1) 1and therefore, I believe that the dissolved oxygen in the water will not exceed 9 mg l-1 at all stages of the water treatment. Before I predict what the results will be like, it is vital that you know from what stages of the sewage treatment did I take water samples. The samples are taken from four sections that will be named raw sewage-this is where the water is still very dirty and hasn't yet been processed at all, air and bacteria tank- here bacteria and air (mainly oxygen) are added to the water, chlorination tank and oxygenation tank. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis2. As a result, I believe that raw sewage will have very low dissolved oxygen content due to the fact that it may have a lot of bacteria that will undergo aerobic respiration and that will use oxygen when

• Word count: 2804
• Level: International Baccalaureate
• Subject: Chemistry

#### How duration affects the rate of electrolysis in a Voltaic Cell

Redox Design and Experiment Design and Conduct an experiment to investigate the effect of ONE FACTOR on redox reactions. Introduction:- The two main components of redox reactions are reduction and oxidation. Reduction is a gain in electrons and the decrease in oxidation number whereas oxidation is the loss of electrons and the increase in oxidation number. Voltaic cells, also known as galvanic cells generate their own electricity. The redox reaction in a Voltaic cell is a spontaneous reaction. For this reason, voltaic cells are commonly used as batteries. Voltaic cell reactions supply energy which is used to perform work. The energy is harnessed by situating the oxidation and reduction reactions in separate containers, joined by an apparatus (known as the salt bridge which primarily completes a circuit and maintains electrical neutrality) that allows electrons to flow. The functions of a voltaic cell are quite simple. There happens to be an anode and a cathode. The positive ions go the negative electrode (anode) whereas the negative ions go to the positive electrode (cathode). Electrons always flow from the anode (where oxidation takes place) to the cathode (where reduction takes place). Electrons flow across wires whereas ions flow across the electrolyte and the salt bridge. Aim:- The objective of this experiment is to see how the time affects the mass of the zinc

• Word count: 2787
• Level: International Baccalaureate
• Subject: Chemistry

#### A Comparison of Strong and Weak Acids and Bases

A Comparison of Strong and Weak Acids and Bases DATA COLLECTION Qualitative Data Table 1.1: The lists of the solutions being used in this experiment and classifying if it is a strong acid or base or a weak acid or base. Solutions Classifications H2SO4(aq) Strong acid HCl(aq) Strong acid HNO3(aq) Strong acid CH3COOH(aq) Weak acid NaOH(aq) Strong base NH3(aq) Weak base H2O(l) Neutral Table 1.2: The appearance of the marble chip used and the magnesium ribbon. Object Appearances Marble chip Coarse, hard , and leaves white powder when held. Magnesium ribbon Shiny silver colour and ductile, i.e. can be bent without breaking it. Note: The chemical formula for marble chip is CaCO3(s) and for magnesium ribbon is Mg(s). Table 1.3: The observations upon reacting different solutions and concentrations of acid with the marble chips, CaCO3(s). Before marble chip is placed in acid solutions. During the reaction between marble chips and acid solutions After reaction has stopped All solutions were colourless As soon as marble chip were placed in the acid solution, bubbles of gas were seen*. Some of the reaction finishes faster than the others. The order in which in this reaction occurs can be seen in Table 1.4. For H2SO4(aq), reaction did occur slowly in the beginning. This reaction however stops. Table 1.4: The order in which the speed of reaction occurs

• Word count: 2752
• Level: International Baccalaureate
• Subject: Chemistry