General Questions and Answers

Determine the resulting pH when 0.040 mol of solid NaOH is added to a 200.0 mL buffer containing 0.100 mol C6H5NH3Cl and 0.500 M C6H5NH₂. The value of Kb for C6H5NH₂ is 4.3 x 10-¹⁰. Use the table below to determine the moles of reactant and product after the reaction of the acid and base. You can ignore the amount of liquid water in the reaction. C6H5NH3(a OH-(aq) → H₂O(l) C6H5NH₂ (ac Before (mol) Change (mol) After (mol)

What is the pH of a solution with 1.25 x 10-4 M HCI? a. 0.000125 b. 10.097 c.-3.903 d. 3.903

Consider the following unbalanced particulate representation of a chemical equation: H = light blue I = purple Write a balanced chemical equation for this reaction, using the smallest integer coefficients possible. Do not include states.

If 6.5 x 10 raised to the power 4 moles of sodium chloride are provided then how many moles of magnesium chloride are produced? * 1.35 x 10 raised to the power 4 moles 3.3 x 10 raised to the power 4 moles 1.3 x 10 raised to the power 5 moles 3.25 x 10 raised to the power 4 moles

You are provided with an unknown solution that contains Group I cations. To 1 mL of this solution you add 6M HCI and obtain a white precipitate. You centrifuge the solution and add an additional drop of 6 M HCI to insure that precipitation is complete. No additional cloudiness formed upon the addition of one drop of HCI and the supernatant solution was decanted and discarded. After washing the precipitate, centrifuging, and discarding the wash, 1-2 mL of water is added to the precipitate, the mixture is heated in a boiling water bath for a few minutes with stirring. The hot mixture is centrifuged and the supernatant transferred to a clean test tube separating it from the remaining white precipitate. One drop of 6M acetic acid is added to the solution. stirred and followed by the addition of a few drops of 1 M K₂CrO4 solution. The formation of a yellow precipitate was observed. To the precipitate that remained in the test tube is added approximately 10 drops of 6 M NH3 and mixed thoroughly. All of the white precipitate dissolved. To the solution 6 M HNO3 is added until it was acidic to litmus and produced a white precipitate. Based on the observations and information provided, identify the ion(s) present in your unknown solution. Pb²+ Hg₂2+ Ag+

How many grams are in 5 moles of KOH? The Molar Mass of K (Potassium) is 39.098 g/mol The Molar Mass of O (Oxygen) is 15.999 g/mol The Molar Mass of H (Hydrogen) is 1.008 g/mol

How many moles are in 395 grams of KMnO4 if the molar mass of KMnO4 is 158 g/mole?

Caroline knows the amount of a compound in moles. To find the number of molecules in the given sample of her compound, which of these values must also be used in her calculation? molecular mass of the compound mass of the sample in grams atomic mass of each element in the compound Avogadro's number

Write the precipitation reaction for sodium chloride in aqueous solution: Be sure to specify the state of each reactant and product. Is sodium chloride considered soluble or not soluble ? A. Soluble B. Not soluble

Water samples containing dissolved substances are called aqueous solutions saline solutions gaseous solutions

Which statement best describes a limiting reactant? the reactant that determines how much is made because it makes the most product the reactant that has greater mass at the beginning of the reaction the reactant that makes the reaction go the fastest the reactant that does NOT make the most product

Two parallel rails with negligible resistance are 1.00E-1m apart and are connected by a 4.800 resistor. The circuit also contains two metal rods having resistances of R1=10.800 and R2=14.500 sliding along the rails (see figure). The rods are pulled away from the resistor at constant speeds v1-4.00m/s and v2=2.00m/s, respectively. A uniform magnetic field of magnitude 0.0100T is applied perpendicular to the plane of the rails. Determine the current in the 4.80ohm resistor.

Use the appropriate metric multiplier to write the following measurement without the use of an exponent. No credit if a metric multiplier is not used. 5.7 x 10-⁹ J

According to the collision theory, in order for a reaction to occur the reactant particles must collide with sufficient energy to overcome the activation energy barrier. proper angle. proper orientation. all of the above.

Select the BEST answer from the choices below. In endothermic reactions, the reaction gets cold because into energy. chemical; nuclear chemical; heat nuclear; chemical heat; chemical energy is changed

A reaction was predicted to produce 32.4 grams of a compound. When the product was measured only 26.1 grams were produced. What is the percent yield of this reaction?

Which statement explains why gases can be compressed? Gas particles flow freely and take the shape of its container. The kinetic energy of gas particles is proportional to the temperature of the gas. Gas particles are extremely small and have relatively large distances between them. Gas particles are relatively large and have extremely small distances between them.

Select all of the true statements regarding chemical equilibrium. The concentrations of reactants and products are equal. The concentrations of reactants and products remain constant. Reactants are being converted to products and vice versa. The rates of the forward and reverse reactions are equal.

How many grams of chlorine can be 64.0 g. of AuCl3 by this reaction? 2AuCl3 --> 2Au + 3Cl2 0.32 g 303.3 g 70.9 g

Arrange the tiles in the table based on the number and shape of each tile. Two tiles have been positioned for you. Continue the sequence to arrange the rest of the tiles in an orderly way. 3 17 8 19 12 6 11 15 13 18 16 20 5 21 10

In the laboratory you dilute 4.06 mL of a concentrated 6.00 M nitric acid solution to a total volume of 175 mL. What is the concentration of the dilute solution?

When H₂(g) reacts with Cl₂(g) to form HCl(g) according to the following equation, 44.2 kcal of energy are evolved for each mole of H₂(g) that reacts. H₂(g) + Cl₂(g) →2HCl(g) Is this reaction endothermic or exothermic? How many kcal of energy are evolved if 1.40 mol of H₂(g) reacts?

Select the correct balanced chemical equation for the reaction of sodium with water to form sodium hydroxide and hydrogen gas (H₂). A. 2 Na (s) + H₂O(l) ---> Na₂(s) + H₂ (8) B. 2 Na (s) + 2 H₂O() ---> 2 NaOH (aq) + H₂ C. Na2 (s) + 2 H₂(1) ----> 2 Na(OH)2 (aq) + H₂ (g) D. Na (s) + H₂O(l) ---> NaOH (aq) + H (g)

When 165 g copper(II) chloride reacts with 72 g sodium nitrate, and copper(II) nitrate and sodium chloride are formed. CuCl₂ +2NaNO3 → Cu(NO3)2 + 2NaCl a) What is the limiting reactant for this reaction?

Figure shows two capacitors that are connected in series to a power source. The capacitance between plates A and B is twice the capacitance between plates C and D. When the power source is switched on, which of the following choices correctly describes the charge stored on each set of plates and the potential drop, across them?

Solve for the missing value: P = 1.5 atm V = 25 L n = 0.55 mole T = ? a 341 K b 68 K c 557 K d 830 K

A double cheeseburger with bacon contains 39 g of fat. Calculate the number of kilocalories from fat. (1 gram of fat = 9 kcal) Round answers to the tens place. 40 kcal from fat 10 kcal from fat 640 kcal from fat 350 kcal from fat 70 kcal from fat

5. How much heat is released by the combustion of 2 mol of methane? Use ΔHrxn=Σ(ΔHf,products)-Σ(ΔHf,reactants) -80.3 kJ -802.5 kJ -1,605.1 kJ -6,420.3 kJ

Sodium hypochlorite (NaOCI) is commonly used as bleaching agent and is formed as a product in the reaction below: NaOH + Cl₂ à NaCl + NaOCl + H₂O a. Is the reaction above for the formation of sodium hypochlorite balanced? If not, then balance this chemic equation. b. What type of reaction(s) is/are being represented for the formation of sodium hypochlorite above? c. Is the reaction for the formation of sodium hypochlorite above an oxidation-reduction (redox) reaction?

When calcium carbonate is heated strongly, carbon dioxide gas is evolved. CaCO3(s) ⇒ CaO(s) + CO2(g) If 5.60 g of calcium carbonate is heated, what volume of CO2 (g) would be produced when collected at STP?

When observed independently, which of the following are indications that a chemical reaction has occurred? Select all that apply. Melting of a solid Evaporation of a liquid Formation of a precipitate Change in odor Temperature change

What is the specific heat of a metal if 40.0 g of the metal absorbs 1912.5 J of energy when heated from 25.0°C to 90.0°C? Round your answer to 2 decimals. Don't forget to include units with your answer.

Why is the product, t-butyl chloride, washed with saturated sodium chloride solution? to dissolve t-butyl chloride to remove residual water to add chloride to the product to add sodium to the product

The freezing point of a cyclohexane sample is 6.20 °C. A solution is prepared by dissolving 0.4660 g of an unknown solute in 36.0 g cyclohexane. The freezing point of the solution is 4.11 °C. (a) Calculate the molar mass, Mm, of the unknown solute below. [kr for cyclohexane is 20.0 °C-kg/mole] (b) The freezing point depression constant, k₁, depends on the solvent, solute or both. [circle your answer] (c) The relationship between AT, and molar mass of a solute is such that as AT, increases, the molar mass increases, decreases, stays the same [circle your answer].

If a hydrogen atom and a helium atom are traveling at the same speed, A. the wavelength of the hydrogen atom will be about 4 times longer than the wavelength of the helium atom. B. the wavelength of the hydrogen atom will be about 2 times longer than the wavelength of the helium. C. the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom. D. the wavelength of the helium atom will be about 2 times longer than the wavelength of the hydrogen atom. E. the wavelength of the helium atom will be about 4 times longer than the wavelength of the hydrogen atom.

A patient takes a 120 mg dose of a certain antidepressant medication. The amount of the medication remaining in the patient from that dose is reduced by half every 7 hours. Which graph shows the amount of the medication, in milligrams, as a function of time, in hours, since the medication was taken?

Magnesium oxide (MgO) forms when the metal magnesium burns in air. (a) If 1.12 g of MgO contains 0.674 g of Mg, what is the mass ratio of magnesium to magnesium oxide? (b) How many grams of Mg are in 956 g of MgO?

Which of the following conditions will increase the rate of a reaction? a decrease in temperature addition of a catalyst removal of a catalyst a decrease in the concentration of the reactants

The half-life of Lead-210 is 22.2 years.. If a sample has 228 mg of Lead-210, how long will it take to have 7 mg or less amount of Lead-210 in the sample? In the ANSWER BOX write the answer in one decimal point. Please DO NOT write the unit.

Balance the following reaction in acidic solution. Cr₂O²- (aq) + HNO₂(aq) → Cr³+ (aq) + NO3-(aq) Fill in the coefficients and substances for the balanced overall equation. Note: Do NOT leave any coeffient fields empty. If the coefficient is 1, choose "1" as opposed to leaving it blank.

The formula for pH is pH = -log [H+], where [H + ] is the hydrogen ion concentration. The pH of a fruit juice is 3.2. What is the hydrogen ion concentration of the juice? The hydrogen ion concentration [H + ] is approximately 10 moles per liter. (Round to the nearest tenth.)

The semiconductor gallium arsenide, GaAs, is used in highspeed integrated circuits, light-emitting diodes, and solar cells. Its density is 5.32 g/cm³. It can be made by reacting trimethylgallium, Ga(CH3)3, with arsine gas, AsH3. The other product of the reaction is methane, CH4. If you reacted 300 g of trimethylgallium with 200 g of arsine, what mass of GaAs could you make?

6. Classify the following reaction as: Combination, Combustion, Single Replacement, Double Replacement, or Decomposition. (Circle the appropriate answer(s)) and briefly explain your choice. ___ H₂S (g) + ___ O₂ (g) -> ___ H₂O(g) + ___SO₂ (g)

If a student's actual yield of extracted fat was 1.33g and her calculated theoretical yield 2.34g, what is her percent yield? 33% 48% 57% 53%

Use the following unbalanced chemical equation to answer the question below: CH4 + O2 → CO2 + H₂O If 1 mole of methane (CH4) combusts, how many moles of H₂O must be produced according to the law of conservation of mass? 1 mole 4 moles 2 moles 6 moles

For the chemical reaction 2 HBr(aq)+Ba(OH)₂ (aq) → 2 H₂O(1) + BaBr₂ (aq) write the net ionic equation, including the phases.

The speed of light in a vacuum is 2.998 x 108 m/s. What is its speed in kilometers per hour (km/h)? What is its speed in miles per minute (mi/min)?

How many picograms are in 7.98 × 10-11 g? How many micrometers are in 8.45 × 10-5 m? How many kilovolts are in 2.16 x 105 V? How many nanoliters are in 8.09 × 10-10 L?

For all of the following calculations, show all your work. If you need more space than is provided, you may do your work on separate pages but they must be attached. At least write your correct answers in the space provided. If you only provide the answers without showing your work somewhere you will not be given full credit. All answers should be clearly identified (boxed off), and all should have the correct number of significant figures and the correct units. 1. How many seconds are in exactly one day to four significant figures?

The Proton Synchrotron particle accelerator at the CERN facility can accelerate protons to energies of 28.0 GeV (gigaelectron volts). What is this energy in joules? A top marathon runner might have a mass of 75.5 kg and can run at an average speed of 4.85 m/s. This gives the runner an average kinetic energy of 888 J. What is this energy in electron volts?