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Chemistry Questions and Answers February 18, 2020

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a) The color standard you prepared is initially 50% product and 50% reactant. What is the percentage of product in the color standard after it has been allowed to sit at 0C for 20 minutes? b) A typical student prepares the color standard 20 minutes before it is used for comparison. Does this delay significantly affect the composition of the color

The dimerization of cyclopentadiene (CSHS) occurs in a simple onestep elementary process as shown below 2 C3H, C10H12 The concentration of CsHs was followed over time and the results are given in the following table Time (s) CSH6 (M) 0.100 M 100 0.049 M 150 0.041 M 200 0.033 M 0.029 M 250 a) What is the average reaction rate between 150 s and 200

The elemental composition of the humic and fulvic acid fractions of an Elliott soil (an Aquic Argiudoll) is given in the table below. Answer the following (Text 4.11, 25 pts): Elemental Content (in g kg-1) of Humic and Fulvic Acids Extracted from an Elliot Soil Compound C H O N S: Humic Acid: C = 581, H = 36.8, O = 341, N = 41.4, S = 4.4 Fulvic

To obtain a high yield of the cobalt complexes it is essential to add the hydrogen peroxide carefully. Consider the following 2C03 2 OH 2C02 H2O2 Required for synthesis 2 H20 (() 02 (g) Undesirable 2 H2O2 (aq) fast at room temperature and slow at 0C Using the infomation above, identify the potential result of each of the following experimental

The following cyclohexane derivative has three substituentsred, green, and blue. Identify each substituent as axial or equatorial, and identify each pair of relationships (redblue, redgreen, and blue green) as cis or trans.

A platter of birdseed is mounted on top of a gasfilled piston. As the birdseed on top of the platter is eaten, the expands isothermally and does 4.17 Jof work. How much heat is transferred during this process gas W 4.11 I

A 25.00 mL sample of a liquid bleach was diluted to 1000mL in a volumetric flask. A 25-mL portion of the diluted sample was transferred by pipet into an Erlenmeyer flask and treated with excess KI, oxidizing the OCl-and Cl-and producing I3-. The liberated I3-was determined by titratingwith 0.09892 M Na2S2O3, requiring 8.96 mL to reach the starch

The amount of ascorbic acid, C6H8O6, in orange juice was determined by oxidizing the ascorbic acid to dehydroascorbic acid C6H8O6with a known excess I3-and back titrating the excess I3- with Na2S2O3. A 5.00 mL- sample of filtered orange juice was treated with 50.00 mL of excess 0.01023 M I3-. After the oxidation was complete, 13.82 mL of 0.07203 M

The level of dissolved oxygen in a water sample can be determined by the Winkler method. In a typical analysis, a 100.0-mL sample is made basic, and treated with a solution of MnSO4, resulting in the formation of MnO2. An excess of KI is added, and the solution is acidified, resulting in the formation of Mn2+and I2. The titrated I2is titrated with

The amount of calcium in physiologic fluids can be determined by a complexiometric titration with EDTA. In one such analysis, a 0.100-mL sample of blood serum was made basic by adding 2 drops of NaOH and titrated with 0.00119 M EDTA, requiring 0.268 mL to reach the end point. Report the concentration of calcium in the sample as milligrams of Ca

After removing the membranes from an eggshell, the shell is dried and its mass recorded as 5.613-g. The eggshell is transferred to a 250-mL beaker and dissolved in 25 mL of 6M HCl. After filtering, the solution containing the dissolved eggshell is diluted to 250 mL in a volumetric flask.

The ratio of alkenes formed by the E2 elimination of 2-bromo-2-methylbutane need not be the same as the ratio formed when the bromide undergoes E1 elimination during solvolysis. Explain this phenomenon and provide a diagram if it is helpful.

Use the Hammond Postulate to explain why free radical brominations are more selective than free radical chlorinations.

A car gets 9.2 kilometers to a liter of gasoline. Assuming that gasoline is 100% octane (C 8 H 18 ), which has a specific gravity of 0.69, how many liters of air (21% oxygen by volume at STP) will be required to burn the gasoline for a 1250-km trip? Assume complete combustion.

Sulfuric acid is commonly used as an electrolyte in car batteries. Suppose you spill some on your garage floor. Before cleaning it up, you wisely decide to neutralize it with sodium bicarbonate (baking soda) from your kitchen. The reaction of sodium bicarbonate and sulfuric acid is 2NaHCO3(s) + H2SO4(aq) Na2SO4(aq) + 2CO2(g) + 2H2O(l) You

In the laboratory, a quantity of I 2 was reacted with excess H 2 to give 0.250 moles of HI. It is also known that the percent yield of this reaction was 59.0%. How many moles of I 2 reacted? (Hint: Write a balanced equation.)

Sodium hydroxide reacts with aluminum and water to produce hydrogen gas: 2 Al( s ) + 2 NaOH( aq ) + 6 H 2 O( l ) 2 NaAl(OH) 4 ( aq ) + 3 H 2 ( g ) What mass of hydrogen gas would be formed from a reaction of 1.10 g Al and 5.57 g NaOH in water?

When a 6.04-g sample of magnesium metal is burned, it produces enough heat to raise the temperature of 1,330 g of water from 24.00 C to 33.10 C. How much heat did the magnesium release when it burned? (The specific heat of water is 4.184 J/g C.)

If 0.30 mol Na is mixed with 0.60 mol N 2 , and 0.038 mol Na 3 N is obtained, what is the percent yield for the reaction? The balanced chemical equation for the reaction is shown below. 6 Na( s ) + N 2 ( g ) 2 Na 3 N( s )

When the reddish-brown mercury(II) oxide (HgO) is heated, it decomposes to its elements, liquid mercury metal and oxygen gas. If 1.49 g HgO is decomposed to Hg, calculate the mass of the pure Hg metal produced. 2 HgO( s ) to 2 Hg( l ) + O 2 ( g )

What mass of oxygen is needed to react with 9.05 gal of methanol according to the balanced equation below? (1.00 gal = 3.79 L, and the density of methanol is 0.793 g/mL.) 2 CH 3 OH( l ) + 3 O 2 ( g ) 2 CO 2 ( g ) + 4 H 2 O( g ) If appropriate, express your answer in scientific notion. (Click on the answer box to show the pallet.)

Decomposition of NI 3 produces nitrogen gas and iodine. How many grams of the reactant would be required to react completely to give 8.32 g of the iodine?

The deployment of airbags during a car accident results from a chemical reaction that, until the 1990s, involved sodium azide, NaN 3 . Sodium azide has since been replaced by less toxic substances that react in a similar way. In older airbags, a crash triggers the decomposition of NaN 3 to form elemental sodium and nitrogen gas, which fills the

Aluminum reacts with chlorine gas according to the following equation shown below. How many moles of Cl 2 are required to react with 0.11 mol of Al? 2 Al( s ) + 3 Cl 2 ( g ) 2 AlCl 3 ( s )

The balanced equation for the reaction of aluminum metal and chlorine gas is 2Al( s ) + 3Cl 2 ( g ) 2AlCl 3 ( s ) Assume that 0.51 g Al is mixed with 0.29 g Cl 2 . (a) What is the limiting reactant (b) What is the maximum amount of AlCl 3 , in grams, that can be produced?

2.Hydrochloric acid is about as strong a mineral acid as sulfuric acid, why would HCl not be a satisfactory catalyst in this reaction? Please draw a reaction scheme to support your answer.

2. Determine the DielsAlder product for the following reaction.How many new bonds and what type of bonds (o or n) are created in the product shown above Please label these bonds in the product.