Thermodynamics – Enthalpy of Reaction and Hess’s Law I. Purpose The purpose of this lab is to verify Hess’s Law through the three reactions of NaOH and HCl‚ NH4Cl and NaOH‚ and NH3 and HCl. The sum of the enthalpies of the first two reactions should equal the enthalpy of the third reaction. II. Background Hess’s Law is used to determine the enthalpy of a reaction from adding two or more preceding reactions. To determine the enthalpies of certain chemical reactions‚ the change in must
Free Enthalpy Thermodynamics Temperature
Decomposition of Sodium Chlorate Mass‚ Moles‚ and the Chemical Equation Introduction: Sodium chlorate is used as a source of oxygen in emergency oxygen generators. So-called oxygen canisters or oxygen candles are found on airplanes‚ submarines‚ even the space station–anywhere where oxygen might be in short supply in case of an emergency. Sodium chlorate decomposes upon heating or in the presence of metals to give oxygen gas. What the chemical equation for the decomposition of sodium chlorate
Premium Chlorine Oxygen Gas
ecosystems. To understand the rates in which certain species’ leaves decay and release the energy stored within them can demonstrate how quickly the energy becomes available to organisms in higher trophic levels. Between plant species the rate of decomposition varies according to leaf structure‚ chemical or physical defence and whether the species is allochthonous or autochthonous. Native species adapt to the predators that feed upon them and the same applies for the predators‚ adapting to the plants
Premium Leaf Species Poaceae
KINETICS OF THE ACID DECOMPOSITION OF THIOSULFATE Aqueous solutions of thiosulfate‚ S2O32-(aq) are stable if neutral or basic‚ but decompose quickly when the thiosulfate is dissolved in acid according to the equation: Sulfur dioxide is a gas at room temperature‚ but is very soluble in water. Sulfur‚ a water insoluble solid‚ forms a colloidal suspension. As a result‚ the solution first becomes cloudy and then opaque. We can take advantage of the developing opacity of the reaction system to do a
Premium Rate equation Chemical kinetics Reaction rate
Measuring the enthalpy change of vaporisation of water You should attempt this part of the activity even if you have not seen the demonstration of the practical. 1. Calculate a value for ∆Hvap for water in KJ mol-1 using the data from the demonstration. Also‚ calculate ∆Hvap from the following data gathered by a student; 8100 J were needed to distil 2.95g of water. a) Explain why the boiling tube was surrounded with expanded polystyrene (or other similar insulation)‚ but the condenser was left
Premium Water Boiling Distillation
Factors affecting the catalytic decomposition of Hydrogen peroxide Please refer to the additional files for tables/graphs. Aim- The purpose of this investigation is to investigate how certain factors affect the catalytic decomposition of Hydrogen peroxide. I will investigate the effect of altering the mass of catalyst used on the rate of the decomposition of Hydrogen peroxide. Introduction- The decomposition of Hydrogen peroxide is a process by which Hydrogen peroxide decomposes into water and
Premium Oxygen Hydrogen peroxide Chemical reaction
Rate of Decomposition of Calcium Carbonate Theory Calcium carbonate‚ CaCO3‚is one of the most abundant minerals on the Earth. More than 4% of the Earth’s crust is composed of calcium carbonate. It is a major component in limestone‚ marble‚ seashells‚ bedrock‚ etc. Limestone and marble have been among the most widely used building materials for more than 5 000 years‚ from the pyramids in Egypt to the Parthenon in Greece and the Taj Mahal in India. In many places‚ limestone is also the foundation
Premium Chemical reaction Carbon dioxide Reaction rate
Thermochemistry: An Ice Calorimeter Determination of Reaction Enthalpy D. F. Nachman 6/23/2010 Abstract: An ice calorimeter was used to study the reaction of magnesium metal and 1.00M sulfuric acid solution: Mg(s) + H2SO4(aq) →MgSO4(aq) + H2(g). We found the experimental molar enthalpy of reaction to be ΔH = –355 ± 17 kJ/mol at 0°C‚ 24% lower than the textbook value of ΔH° = –466.9 kJ/mol‚ reported at 25°C. Introduction Whether a chemical reaction occurs spontaneously or is driven by an outside
Premium Energy Enthalpy Thermodynamics
From the experimental data and through its analysis‚ the enthalpy of combustion for the five alcohols were determined; methanol‚ ethanol‚ propanol‚ butanol‚ and pentanol. As the line of best fit in the graph suggests‚ the enthalpy of combustion increased as the sizes of the molecules increased. This was predicted in the hypothesis and proves it to be correct. As seen on the graph‚ the enthalpy of combustion increases from 140kJ/mol for methanol‚ which has the smallest molecular mass‚ to 530kJ/mol
Premium Chemistry Oxygen Enzyme
The thermal decomposition of nitrates – ‘writing with fire’ 31 A message is written on filter paper with a solution of sodium nitrate and is then dried‚ rendering it invisible. Applying a glowing splint to the start of the message makes the treated paper smoulder and the message is revealed as the glow spreads its way through the treated paper. Lesson organisation The demonstration takes about 10 -15 minutes. It could be a student activity‚ but with a large class it will need a well
Premium Ammonia Paper Nitrogen