Explain how you determined the order of the reaction in H2O2 and KI. The rate determining step, or slow step, must be step 1.
Dropper Teacher Preparation Make a detergent solution by adding 1 teaspoon of liquid dish detergent to 2 tablespoons of water. Divide this detergent solution equally into one small cup for each group. Procedure Add 10 mL of hydrogen peroxide to a graduated cylinder. Add 1 drop of detergent solution.
Swirl gently and watch the solution for any bubbling. Explain to students that the detergent is added only to make bubbles if any gas is produced. Since the breakdown of hydrogen peroxide produces oxygen gas, bubbling shows that the hydrogen peroxide is breaking down or decomposing.
The lack of bubbling shows that not much oxygen gas is being produced. Use the end of a popsicle stick to add a small amount of yeast to the hydrogen peroxide in the graduated cylinder and swirl. Place the graduated cylinder on the table and watch for any bubbling. Hold the graduated cylinder to see if there seems to be any change in temperature.
Expected Results Before the yeast is added, there is no observable bubbling. After the yeast is added, bubbling will cause foam to move up the graduated cylinder.
Also, the graduated cylinder should feel a little warmer because the decomposition of hydrogen peroxide releases energy. Energy changes in chemical reactions will be investigated in more detail in Chapter 6, Lesson 7. What clues did you have that a chemical reaction occurred in this activity?
Tell students that a change in temperature is also a sign that a chemical reaction may be occurring. Endothermic and exothermic chemical reactions will be addressed in Chapter 6, Lesson 7. What is the catalyst in this activity? A substance in yeast.
What evidence do you have that hydrogen peroxide decomposed faster when you added yeast? Bubbles of oxygen gas were produced after the yeast was added.
When you write the chemical equation for this reaction, should yeast be included on the product side of the chemical equation? Explain to students that the catalyst in the yeast does not end up in the products but is a substance that helps the decomposition happen faster. Sometimes a catalyst is written above or below the arrow in a chemical equation, but it is never included with the reactants or products.
In general, catalysts work by providing a place where reactants can come together to react. Explain to students that cells in yeast and other organisms contain a catalyst called catalase. Through normal cell processes, living things produce hydrogen peroxide in their cells.
But hydrogen peroxide is a poison so the cells need a way to break it down very quickly. Cells contain catalase, which breaks down hydrogen peroxide at a very fast rate. A single molecule of catalase can catalyze the breakdown of millions of hydrogen peroxide molecules every second.
Students may continue to explore the effect of catalase on hydrogen peroxide by adding a piece of raw fresh potato to a small amount of hydrogen peroxide. Extend Have students identify the changes that occur when copper II sulfate reacts with a piece of aluminum foil.
This is a reaction between copper II sulfate and aluminum. This type of copper ion is called copper II. This ion is made up of more than one atom. It is one of the polyatomic ions discussed in Chapter 4, Lesson 3.
There are several interesting aspects of the reaction between copper II sulfate and aluminum, but it is different from the other reactions students have seen so far. In this reaction, the movement of electrons, rather than entire atoms, ions, or molecules, causes the reaction to occur.
This particular reaction is fun to do because it is exothermic, generates a gas, and copper metal appears as aluminum metal disappears. Salt can be considered a catalyst in the reaction but has a different role than most catalysts.Specific Impulse.
The specific impulse of a rocket, I sp, is the ratio of the thrust to the flow rate of the weight ejected, that is where F is thrust, q is the rate of mass flow, and g o is standard gravity ( m/s 2)..
Specific impulse is expressed in seconds. When the thrust and the flow rate remain constant throughout the burning of the propellant, the specific impulse is the time for.
How to balance a chemical reaction by making sure you have the same number of atoms of each element on both sides.
There are three types of decomposition reactions: Thermal decomposition reactions; Elctrolytic decomposition reactions; Photo decomposition reactions. Thermal decomposition - such reactions are usually endothermic, since energy in the form of heat is required to break the bonds of . A decomposition reaction is a type of chemical reaction in which a compound is separated into its component parts. It is important to understand how to write and balance decomposition reactions because they occur within many types of chemical experiments. Predict if a reaction will occur when you combine aqueous solutions of iron (II) chloride with aqueous sodium carbonate solution. If the reaction does occur, write a balanced chemical equation showing it.
Average vs. Instantaneous Reaction Rates average rate of reaction - rate of reaction over some time interval ex. What is the rate of decomposition of H 2O 2 between and seconds? instantaneous rate of reaction - rate of reaction at a speciﬁc time point ex.
What is the rate of decomposition of. In this lab, we will perform the catalyzed decomposition of hydrogen peroxide under various conditions. We will record the trials using a gas pressure sensor in a lab quest and analyze graphs of the data.
From this analysis, we will determine the rate constant, the activation energy and the rate law. Obtaining rate data, interpreting rate data, orders of reaction and rate expressions a.
Examples of obtaining rate data. A BRIEF REVIEW OF METHODS OF COLLECTING RATE DATA. The speed or rate of reaction is the rate of removal of reactant or the rate of formation of product. The separation of a substance into simpler substances or basic elements.
Decomposition can be brought about by exposure to heat, light, or chemical or biological activity.