Determine the reactions at a and c when a 5 0 b 5 30


Introduction


To determine the reactions at a and c, we must first balance the equation. This can be done by adding 5 O2 to the left side and 2 H2O to the right side. The balanced equation is as follows:

5 0 2H + 5 30 2H O → 7H 4O + O

Now that the equation is balanced, we can look at the individual reactants and products to determine which are being oxidized and which are being reduced. In this reaction, H2 is being oxidized to H2O while O2 is being reduced to H2O.

Theoretical Background

In order to determine the reactions at a and c, we need to consider the forces acting on the beam. The force at point a is the sum of the forces acting on the beam to the left of point a. The force at point c is the sum of the forces acting on the beam to the right of point c.

Equilibrium

In a chemical reaction, equilibrium is the state in which the reactants and products have the same concentrations. It is important to remember that this does not mean that the concentrations are not changing, but rather that they are not changing in response to any changes in the system. In other words, they are at a constant ratio.

In order to understand how equilibrium is reached, we must first understand what happens when a reaction starts. When a chemical reaction starts, there is usually an excess of reactants. This means that the products will start to form as the reactants are used up. However, as more products are formed, the concentration of reactants decreases. This makes it harder for them to collide and react with each other. At the same time, the products are now starting to get in the way of each other and slow down their own formation. So, as the reaction goes on, the rate of product formation will slow down and eventually stop even though there are still reactants present. This is because there is an equal concentration of reactants and products (or catalysts) present and thus no net change in either direction can occur.

Le Chatelier’s Principle

Le Chatelier’s Principle states that when a system at equilibrium is subjected to a change in conditions, the system adjusts so as to minimize the effect of the change. In other words, the system will shift in a direction that opposed the change. For example, if a reaction is at equilibrium and pressure is increased, the reaction will shift to the side with fewer gas molecules in order to reduce the pressure.

Experimental Procedure

To determine the reactions at points a and c, set up the experiment as shown in Figure 1. First, set the dial on the force meter to 0 N. Then, place the slotted weight on the hanger and attach the hanger to the force meter using the string. Make sure that the string is taut. Next, add the 30 g weight to the other end of the hanger. Finally, add the 5 g weight to the middle of the hanger. Observe and record the readings on the force meter.

Materials


-2 glass beakers (100 mL)
-1 plastic transfer pipette
-0.5 g of solid sodium bicarbonate (NaHCO3)
-10 mL of 3% hydrogen peroxide (H2O2) solution
-Wash bottle filled with distilled water

Procedure:

  1. Fill one beaker with 50 mL of boiling water and the other with 30 mL of cold water.
  2. Place the 0.5 g of NaHCO3 into the glass container with the boiling water. Stir until it has dissolved completely. Use the wash bottle to add distilled water to the solution until the 100 mL mark on the beaker is reached.
  3. Transfer 10 mL of H2O2 solution into the second beaker containing cold water using the plastic transfer pipette. Gently stir the contents of the beaker until mixed well.
  4. Record your observations in the table below.
    Apparatus

    The following items will be needed in order to complete this experiment:

-One 250 ml Erlenmeyer flask
-One stopper that fits the Erlenmeyer flask
-One thermometer (capable of reading temperatures between 0 and 100 degrees Celsius)
-One 125 ml graduated cylinder
-One 250 ml beaker
-Two 100 ml beakers
-Wax crayon or permanent marker
-Lab notebook
-Pen or pencil

Procedure

  1. Using a clean, dry test tube, add 5 mL of 0.1 M aqueous sodium bromide (NaBr) solution.
  2. To this solution, add 5 drops of 30% hydrogen peroxide (H2O2) solution.
  3. Observe the contents of the test tube for the development of a white precipitate. Record your observations in your lab notebook.
  4. Repeat steps 1-3 using 10 mL of 0.1 M aqueous sodium bromide (NaBr) solution and 10 drops of 30% hydrogen peroxide (H2O2) solution. Record your observations in your lab notebook.
    Data and Observations
    When 50 mL of 0.1 M hydrochloric acid is mixed with 50 mL of 0.1 M sodium hydroxide, a clear, colorless solution is formed.
    Data
    In order to determine the reactions at a and c, we need to know the data and observations that were made during the experiment. This information will help us understand what happened during the experiment and why the results were observed.
    Observations
    When 5.0 grams of sodium metal is added to 5.0 mL of water, the temperature of the water increases from room temperature (22.0 degrees Celsius) to 30.0 degrees Celsius. A hot, violent reaction takes place as the sodium metal begins to produce hydrogen gas and heat. The evolved hydrogen gas collects in the graduated cylinder above the water line. After all of the sodium has reacted, the temperature of the solution stabilizes at 30.0 degrees Celsius and no further reaction appears to take place.
    Analysis and Conclusion
    The given equation is not balanced. In order to balance the equation, we must determine what the missing reactant is and what the products are. We can then find the balanced equation and calculate the amounts of each reactant and product.
    Analysis

    In order to determine the reactions at a and c, we must first know the values of a and b. In this case, a is 5 and b is 30.

We can use the quadratic equation to solve for c.

c = (-5 +/- sqrt(5^2 – 4(5)(30)))/2(5)

c = (-5 +/- sqrt(25 – 600))/10

c = (-5 +/- sqrt(-575))/10

Since we cannot take the square root of a negative number, there is no real solution for c. This means that the reactions at a and c cannot be determined.

Conclusion

Based on the information gathered, it can be concluded that light roasts have a slightly higher concentration of caffeine than dark roasts. The perfect roast is a personal choice that is sometimes influenced by national preference or geographic location. Within the four color categories, you are likely to find common roasts as listed below. It’s a good idea to ask before you buy. There can be a world of difference between roasts.


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