General Questions and Answers

Balance the following equations. Please use additional paper to show your work! a. HCI + Ca ---> CaCl₂ + H₂ b. N₂ + O₂ ---> N₂O c. AlBr₃ + K ---> KBr + Al d. FeO + PdF₂ ---> FeF₂ + PdO e. P₄ + Br₂ ---> PBr₃ f. LiCI + Br₂ ---> LiBr + Cl₂ g. PbBr₂ + HCl ---> HBr + PbCl2 h. CoBr₃ + CaSO₄ ---> CaBr₂ + Co₂(SO₄)₃ i. Mn+ HI ---> H₂ + Mnl₃ j. Li₃PO₄ + NaBr ---> Na₃PO₄ + LiBr

Formic acid, HCOOH, is a weak acid with a Ka equal to 1.8x10^-4. What is the pH of a 0.0115 M aqueous formic acid solution? A) 5.68 B) 2.84 C) 1.94 D) 0.90

Which of the following is(are) true about a double covalent bond. a. Two electrons are transferred between two atoms. b. Four electrons are transferred between two atoms. c. None of these is correct d. Four electrons are shared between two atoms. e. Two electrons are shared between two atoms.

A solution of a coordination complex absorbs light with a wavelength 670 nm. (a) Use the color wheel on page 3 of the packet to determine the color of visible light absorbed by the complex. (b) Recall that the observed color of the complex is the complement of the color of light absorbed. Based on this, predict the observed color of the complex.

How many grams of Na (22.99 g/mol) are there in 5.00 grams of Na₂CO₃ (105.99 g/mol)? 2.17 g 1.08 g 0.00410 g 0.542 g 0.644 g

At 900° C titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride. Part A: Write a balanced equation for this reaction. Express your answer as a chemical equation. Identify all of the phases in your answer.A chemical reaction does not occur for this question. Part B: What is being oxidized, and what is being reduced? Express your answers as chemical formulas separated by a comma.

Which of the following is likely to change the activation energy of a reaction? a. increasing the concentration of reactants b. adding a catalyst to the reaction c. increasing the temperature of the reaction d. all of these e. none of these

Recall that gaseous propane requires much more space than liquefied propane - one mole of ANY gas at STP will occupy 22.4 L of space. How much space is needed to hold 6.72 mol gaseous propane? (Round answers to 2 decimal places - only numerals!)

The partial pressure of O₂ in your lungs is about 100. mmHg. Calculate the concentration of O₂ (in grams per liter) that can dissolve in water at 37 °C when the O₂ partial pressure is 93.0 mmHg. The Henry law constant for O₂ at 37 °C is 1.5x10‾⁶ mol L‾¹ mmHg‾¹. [O₂] = ________g/L

What is the best procedure to prepare 0.500 L of a 0.200 M solution of Li3PO4? The molar mass of Li3PO4 is 115.8 g/mol A) Weigh 11.6 g of solute and add 0.500 L of water. B) Weigh 23.2 g of solute and add 0.500 L of water. C) Weigh 11.6 g of solute and add sufficient water to obtain a final volume of 0.500 L. D) Weigh 23.2 g of solute and add sufficient water to obtain a final volume of 0.500 L.

Which will have a greater volume at STP, 32.0 g of O₂ or 32.0 g of O₃? O₂ O₃ They will have the same volume

Select the FOUR correct answers about protein structure There is no cost in conformational entropy of folding the protein into one specific native fold A protein domain is an independently stable region of a protein The native fold has a large number of favorable interactions within the protein In soluble proteins, the hydrophilic amino acid residues tend to be in a densely packed core, and the hydrophobic amino acid residues tend to be on the protein surface Active site, metal binding site, DNA binding residues, fold- determining residues, and usually core of protein are less conserved that surface Different conformations of a protein can be achieved without breaking covalent bonds and are achieved through rotations about bonds A motif is an independently stable region of a protein with a hinge region Interaction of N-H and C=O of the peptide bond leads to local regular structures such as a-helixes and b-sheets

Patients suffering from respiratory disorders are often treated in oxygen tents in which the atmosphere is enriched in oxygen. What is the partial pressure of O2 in an oxygen tent consisting of 35.% O₂ for an atmospheric pressure of 742 mm Hg?

In the synthesis reaction between aluminum and oxygen gas, aluminum oxide is produced. This equation is: 4 Al(s) + 3 O₂(g) -> 2 Al₂O₃(g). How many moles of aluminum are needed to form 6.44 moles of aluminum oxide? Round answers to 2 decimals, and no units need to be entered!

A chemist needs to mix a 20% alcohol solution with a 50% alcohol solution to get 15 liters of a 36% alcohol solution. How many liters of the 20% solution should be used? How many liters of the 50% solution should be used? Use this many liters of the 20% solution: and this many liters of the 50% solution:

How many moles of oxygen are in a 7.68 L container at 355 K and exerting a pressure of 8.57 atm on the walls of the container?

When the volume of a gas is changed from temperature L to 4.50 L, the will change from 38.1°C to 15.0°C.

A gas that exerts a pressure of 15.6 psi in a container with a volume of L will exert a pressure of 25.43 psi when transferred to a container with a volume of 1.895 L.

What is the hybridization of the central atom in CCl₄? What are the approximate bond angles in this substance? What is the hybridization of the central atom in AlCl₃? What are the approximate bond angles in this substance?

At standard temperature and pressure, four grams of helium gas occupy a volume of 22.4 L. Under the same conditions, what volume would 2 grams of hydrogen gas occupy? (A)22.4L (B)44.8 L (C)5.6 L (D)11.2 L

The barometric pressure in a cavern was measured using a mercury barometer. A value of 748.9 mm Hg was obtained. What would the value be in atm?

In order for the Combined Gas Law to be used, what variable must be the same under both sets of conditions? (A) pressure (B) the amount (number of moles) of gas (C) temperature (D) P, V, and I must all be constant (E) volume

Note: You may enter a number using e-notation. For example, 1.3 x 10‾⁸ would be entered as 1.3e-8. Set the pH = 7.00. Press Enter. What is [H₃O⁺]?

a Choose the balanced equation for the reaction, even if the reaction is reactant-favored. NH₄⁺(aq) + Br‾(aq) (A) NH₄⁺(aq) + Br‾(aq) --> NH3(aq) + HBr(aq) (B) 2NH₄⁺(aq) + 2Br‾(aq) --> 2NH3(g) + Br₂(l) + H₂(g) (C) NH₄⁺(aq) + 2Br‾(aq) --> NH3(g) + Br₂(l) (D) NH₄⁺(aq) + Br‾(aq) --> NH₄Br(s)

Propyl acetate (C₅H₁₀O₂; molecular weight = 102.13 g/mol) is a water-soluble ester with a characteristic pear-like odor. A lab technician dissolves 5 g of this ester in enough water to give 250 mL of solution. Calculate the molarity of this solution, showing ALL your work.

Molecular iodine, l₂ (Molar mass = 253,81 g/mol) is produced by the reaction of 3.16 g of CuCl₂ (Molar mass = 134.45 g/mol) according to the following equation: 2CuCl₂ + 4 KI —> 2Cul + 4 KCI + l₂ How many grams of l₂ is produced?

How much carbon dioxide emissions will you cause by using your 250 watt laptop for 8 hours? Express your answer rounded to the nearest hundredth of a pound of carbon dioxide. ________lb of CO₂

Cu(s) + 2NO₃‾ (aq) + 4H⁺(aq) ---> Cu²⁺(aq) + 2NO₂(g) + 2H₂O(aq) Which of the following statements are true? A. Oxidation number of N in NO₂ is +4 B. NO₃‾ is the oxidizing agent C. Cu oxidize to Cu²⁺ D. Oxidation number of N in NO₃‾ is -1 E. Oxidation number of H⁺ is +4 F. Oxidation number of N in NO₃‾ is +5 G. H⁺ reduced to H₂O H. Oxidation number of Cu is 0 I. Oxidation number of Cu²⁺ is +2 J. NO₃‾ reduced to NO₂ K. Cu is the reducing agent

View the following configuration for a Phosphorus atom: 1s²2s²2p⁶3s¹3p³4s¹ Is this atom in its ground state or excited state? If excited, describe which electron has jumped and to where it has jumped.

Determine the oxidation states of the two elements – barium and chlorine - in the compound BaCl₂.

In experiment P7 of the phys chem practicals, the second-order reaction between iodomethane and a hydroxide ion is studied. The following measurements are performed to determine the rate constant, k: 8.3905 g of KOH and 9.7231 g of iodomethane are measured with an analytical balance, a time of up to 3600 s is measured with a stopwatch, a 100 ml volumetric flask with an accuracy of 0.2 ml and a 50 ml volumetric flask with an accuracy of 0.12 ml are used to prepare the reactants mixture, and a burette with divisions of 0.1 ml and aliquots of up to 1 ml is used to determine the hydroxide ion concentration. Calculate the minimum error due to stopwatch. a. 0.0014 b. 0.00014 c. 0.00027 d. 0.0027

Which one of the following statements about synaptic function is incorrect? 1. If an excitatory synapse generated a 2 mV EPSP in a neuron's dendrite and an inhibitory synapse generated a 2 mV IPSP in a neuron's cell body, the inhibitory synapse would have a stronger influence on action potential generation in the postsynaptic cell. 2. If one applied a toxin to the presynaptic membrane that blocked the opening of voltage-gated K^+ channels, transmitter release would decrease. 3. At an excitatory synapse, binding of the neurotransmitter to its postsynaptic receptor generates net inward current across the postsynaptic membrane. 4. If one applied a toxin to the presynaptic membrane that blocked the opening of voltage-gated Ca^2+ channels, the amplitude of the postsynaptic potential would increase.

12. a. Write out the full electron configuration for Scandium (Sc) b. Would the second ionization energy for Sc be high or low? Explain c. Would the fourth ionization energy for Sc be high or low? Explain

Enter the symbol for the element being described. Enter only the elemental symbol, not the name. Note: If there is more than one possible correct answer, full credit will be given for any you choose. Element with 4 valence electrons in the 5th energy level:

Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number, and then find its exact value. cos 38 cos 22° - sin 38° sin 22°=

If you are given 3.00 g of Sodium Chloride in excess sulfuric acid, how many grams of Sodium Sulfate with be produced? Show your work and include proper number of significant figures. 2NaCl + H2SO4 ⇒ Na2SO4 + 2HCI

When calcium carbide and water react, the produce acetylene gas (C₂H₂) and calcium hydroxide. The reaction is expressed by the following equation: CaC₂(s)+ H₂O(l) --> C₂H₂(g) + Ca(OH)₂(aq). How many grams of water are needed when more than enough calcium carbide is added to produce 9.85 g of acetylene gas?

Create the equation of a quadratic polynomial, in standard form, that has zeroes of -5 and 2 and which passes through the point (3, – 24). Sketch the graph of the quadratic below to verify your result.

Some dietitians recommend drinking six 8-oz glasses of water each day. If your drinking water contains the maximum contamination level for arsenic, 0.010 ppm, calculate how much arsenic would you consume in a week following this recommendation.

If a mini-van gets 33 miles per gallon on average, how much carbon dioxide is emitted into the atmosphere when the mini-van travels 310 miles? Express your answer rounded to the nearest tenth of a pound of carbon dioxide. __________Ib of CO₂

A 20.00 mL sample of vinegar was titrated with 1.50 M NaOH. If it took 18.50 mL of NaOH to reach the equivalence or stoichiometric point, what is the mass percent of acetic acid (CH₃CO₂H) in the vinegar? Assume the density of vinegar is 1.00 g/mL. CH₃CO₂H + NaOH --> H₂O + CH₃CO₂Na

For Acid Base reaction, identify the acid, base and conjugate pairs, a. HCI + NH₃ -> NH₄⁺ + Cl‾ b. CH₃COOH + HO -> H₃O⁺(aq) + CH₃COO‾ c. PO₄³‾ + HNO₃ -> NO₃ + HPO₄²‾ d. HCO₃‾ + HCI -> H₂CO₃ + Cl‾

A student performed the experiment "Titration of Acetic Acid in Vinegar". However, he accidentally over-titrated (added more NaOH beyond the stoichiometric or equivalence point). What effect would this have on his results? The calculated concentration of acetic acid would appear higher than the actual value. The calculated concentration of acetic acid would appear higher or lower than the actual value depending on how much he over-titrated. The calculated concentration of acetic acid would not be affected, or would just be the same as the actual value. The calculated concentration of acetic acid would appear lower than the actual value.

One student wants to know if atom number 2 below is the same as atoms 1 and 3 below. atom #of electrons #of protons #of neutrons mass# 1 10 12 ? 24 2 12 ? 13 25 3 12 12 14 ? Which argument correctly supports that claim? Atom 2 is the same, because it has the same number of protons as atoms 1 and 3. Atom 2 is not the same, because it has a different number of neutrons than atoms 1 and 3. Atom 2 is not the same, because the mass number is different from atoms 1 and 3. Atom 2 is the same, because it has just as many electrons as the number of protons in atoms 1 and 3.

How much carbon dioxide will you prevent from entering the atmosphere in one year, if you replace a 150-watt light bulb with a CFL bulb that uses 13 watts in a fixture that you have on for 11 hours per day? Express your answer rounded to the nearest tenth of a pound of carbon dioxide. lb of CO2

Here is the electron configuration for Sulfur: 1s²2s²2p⁶3s²3p⁴ a. Would a single atom of sulfur be stable or unstable? b. Sulfur become a -2 ion. What sublevel are these 2 gained electrons put into? c. If sulfur gained 2 electrons what element does it now have the same electron configuration as? Why is this stable?

The ability of carbon to attract electrons is: 1. greater than that of nitrogen, but less than that of oxygen 2. less than that of nitrogen, but greater than that of oxygen 3. greater than that of nitrogen and oxygen 4. less than that of nitrogen and oxygen

Aniline has pka = 4.63. 3-Bromoaniline has pka = 3.58. Answer these questions to determine which is the stronger base. The value of Kb reflects the strength of the base, so we need to find the value of Ka from the pKa. What are the values of Ka for aniline and 3-bromoaniline? Ka(aniline) = Ka(3-bromoaniline) =

Write an equation to describe the proton transfer that occurs when this base is added to water. HSO₄‾ HSO₄‾ + H₂O ⇌ Write an equation to describe the proton transfer that occurs when each of these bases is added to water. CH₃NH₂‾ CH₃NH₂‾ + H₂O ⇌ Write an equation to describe the proton transfer that occurs when each of these bases is added to water. F‾ F‾ + H₂O ⇌ Write an equation to describe the proton transfer that occurs when each of these bases is added to water. H₂PO₄‾ H₂PO₄‾ + H₂O ⇌

Instructions: Answer the following questions in canvas. Attached is a document containing the questions incase you prefer to have the questions on your devices. Imagine a newly appointed chemist in the Walgreens you work at has to prepare 200ml of a 0.05M aqueous solution of potassium chloride (KCI). 1. What does he need to measure first to make the solution? 2. Please determine the grams of KCl he needs to prepare the required solution, in case, he asks for your help. 3. After sometime, he comes back to you and says he accidently prepared 200ml of 1 M KCl solution. He would prepare a fresh one based on your calculations but, unfortunately, he used up all the KCl. How would you solve this situation?