General Questions and Answers

Name each of the following polyatomic ions: CN- = SO4 -2 = OH- = NHa+ = CrO4 -2 = NO3- = PO4 -3 = C2H3O2- =

Compute the wavelength in air of ultrasound with a frequency of 46 kHz if the speed of sound is 344 m/s.

When a sugar cube dissolves in coffee, it is an example of which of the following? Select the correct answer below: a physical change a chemical change a change in an extensive property none of the above

You may want to reference (Page) Section 7.5 while completing this problem. Calculate the empirical formula for each of the following substances. A chemical reaction does not occur for this question.

If you heated the copper at the end to dry it in an evaporating dish over a beaker of boiling water and you let the water in the beaker boil away (exposing the dish to excess heat), would you expect that to result in an incorrecity high or incorreclty low amount of copper recover at the end of the sequence

The density of chromium is 7.19 g/mL. If you have a 6.90 g piece of chromium, what volume will it occupy (in milliliters)? Round your answer to the nearest thousandth.

What is the maximum number of electrons in an atom that could have the quantum numbers of n = 4,l = 0 ?

An 8.6 g rock sample is added to a graduated cylinder filled with water, causing the level to increase from 12.1 mL to 14.9 mL. What is the density of the rock sample? Select the correct answer below: 2.7 g/mL. 3.9 g/mL. 3.1 g/mL. 2.8 g/mL

Calculate the number of moles of C₂ Hỏ (nc₂H₁ ) in 3.97 × 1023 molecules of C₂ H6. Express your answer using three significant figures. nc₂ H6 = moles of C₂H6

Robert was able to travel 241.0 miles in 4.000 hours and used 38 liters of gasoline. What was Robert's speed in feet per second? (5,280 ft = 1 mi)

Rubidium has two naturally occurring isotopes, 85Rb (relative mass 84.9118amu) and 87Rb (relative mass 86.9092amu). If rubidium has an average atomic mass of 85.47amu, what is the abundance of each isotope (in percent) - show work?

Calculate the number of moles of C₂H6 (nC2H6) in 3.97 × 10^23 molecules of C₂H6. Express your answer using three significant figures.

Determine the molality of a KNO3 solution that is prepared by dissolving 39.5 g KNO3 into 575 mL water. The density of water is 1.00 g/mL. a. 0.000679 m b. 0.0687 m c. 0.679 m d. 68.7 m e. 6950 m

3. Rank the compounds below from lowest to highest viscosity based on their structures. (Hint: hydrogen bonds formed between molecules with N-H groups are weaker than those formed between molecules with O-H groups.) A. 1-propanol, CH3CH₂CH₂OH B. propane, CH3CH₂CH3 C. propanal, CH3CH₂CH=0 D. 1-propanamine, CH3CH₂CH₂NH₂

How many grams of S are in 26.3 g of (C3H5)2S? Express your answer to three significant figures.

Limiting Reagent In the reaction below between calcium nitrate and sodium carbonate in water a solid precipitate of calcium carbonate, CaCO3, is formed. Ca(NO3)2(aq) + Na₂CO3(aq) → CaCO3(s) + 2NaNO3(aq) A) What is the expected (theoretical) yield of calcium carbonate, when 5.0473 gram of calcium nitrate reacts with 2.5452 g sodium carbonate? Show your calculations B) What is the percentage yield when 2.2514 gram of product is recovered? Show your calculations

When a protein is heated and denatured, the interactions stabilizing the protein that are most affected and lead to denaturation are hydrogen bonds subunit-subunit crosslinks salt bridges disulfide bonds All of the Above

A compound contains 10.06% carbon, 89.10% chlorine and 0.84% hydrogen. a. What is the empirical formula? (3 marks) a. It is found to have a molar mass is 119.6 g/mol what is the molecular formula? (2 marks)

Given the reaction: Fe³+ (yellow) + SCN (colorless) <--> [FeSCN]²+ (dark red) If Fe3+ is added to the solution: The solution becomes colorless The solution turns darker red No changes in color occur The solution becomes more yellow

HCN is an acid. Which one is its conjugate base and why? CN because acids donate protons to form conjugate bases. H₂CN+ because acids accept protons to form conjugate bases. CN+ because acids donate electrons to form conjugate bases. H₂O because water is a solvent.

Determine AG for the reaction 3 N₂(g) + 2 O₂(g) →→ 6 NO(g) at 223°C. ΔH° +257.7 kJ/mol ΔS°= +213.7 J/mol K

Which of the following statement about thermodynamic systems and state functions is CORRECT? Enthalpy is a path function. A closed system allows the transfer of energy but not mass. Work is a state function. An isolated system permits the transfer of mass and energy.

An aerosol can has a pressure of 1.86θ atm. What is this pressure expressed in units of mm Hg with a correct number of significant figures? (Use 1 atm=76θ mmHg) 1414 mm Hg 1.86θ mm Hg 141θ mm Hg 1413.6 mm Hg

What is DH° for the following reaction? YOU MUST WRITE ALL CALCULATIONS OTHERWISE YOU WILL NO BE GRANTED FULL CREDIT 2C₂H₂(g) + 50₂(g) Ⓡ 4CO2(g) + 2H₂O(l) Substance DHºf (kJ/mol) C₂H₂(g) +226.7 CO₂(g) -393.5 H₂O(l) -285.8 +2599.0 kJ -452.6 kJ -1692.2 kJ +1692.2 kJ -2599.0 kJ

Which of the following statements is incorrect concerning the thermochemical equation below? 2SO3(g) Ⓡ2SO2(g) + O₂(g); DH° = 198 kJ The enthalpy of the reactants exceeds that of the products. For every mole of SO3(g) consumed, 99 kJ of heat at constant pressure is consumed as well. For the reaction 2SO₂(g) + O₂(g) Ⓡ2SO3(g), DH = -198 kJ. The external pressure is 1 atm. The reaction is endothermic.

Gaseous ethane (CH3 CH3) reacts with gaseous oxygen gas (O₂) to produce gaseous carbon dioxide (CO₂) and gaseous water (H₂O). What is the theoretical yield of water formed from the reaction of 2.71 g of ethane and 20.1 g of oxygen gas? Round your answer to 3 significant figures.

Chromium has an atomic mass of 51.9961 u and consists of four isotopes, 50 Cr, 52Cr, 53Cr, and 54Cr. The 52Cr isotope has a natural abundance of 83.79% and an atomic mass of 51.9405 u. The 54Cr isotope has a natural abundance of 2.37% and an atomic mass of 53.9389 u. The natural abundances of the 50 Cr and 53Cr isotopes exist in a ratio of 0.4579:1, and the 50 Cr isotope has an atomic mass of 49.9460 u. Determine the atomic mass of the 53Cr.

Using the reaction bank, devise a synthetic route (should use several reactions) to convert the starting material into the product. Remember, order is important.

Use the reaction equation below to answer questions (a) and (b) that follow. Balance the equation above using the appropriate coefficients. b. Calculate the amount of gold chloride produced when 37 grams of silver chloride are reacted with adequate gold sulfate.

The nonvolatile, nonelectrolyte saccharin, C₂H5NO3S (183.2 g/mol), is soluble in ethanol CH3CH₂OH. How many grams of saccharin are needed to generate an osmotic pressure of 6.70 atm when dissolved in 275 ml of a ethanol solution at 298 K..

Study this chemical reaction: Ca(s)+ZnCl₂(aq) ⇒ Zn(s)+CaCl₂(aq) Then, write balanced half-reactions describing the oxidation and reduction that happen in this reaction.

Lead (II) nitrate reacts with potassium iodide to produce lead (II) iodide and potassium nitrate according to the chemical equation below. Pb(NO3)2 +KI →→→ Pbl2 + KNO3 What are the coefficients of the balanced chemical equation? 1:3:1:3 2:1:2:2 1:2:1:2 1:5:3:5

Which statement best rationalizes ASsys for combustion of methane? CH4(g) + 2O2(g) → CO2(g) + 2H₂O(g) This is a combustion reaction so ASsys will be a large negative number. This is a combustion reaction so ASsys will be a large positive number. There are no changes of state and no change in Anxn so ASsys will be small. Combustion reactions are exothermic, so ASsys also will be a large negative number

A chemical equation is shown below: CuCl2 + H₂S → CuS + HCl What is the molar ratio for the chemical reaction when the equation is balanced? 1:2:1:2 2:1:1:2 2:2:2:4 1:1:1:2

Sharing of electrons occurs when two nonmetals form a compound with a covalent bond. When a metal and a nonmetal combine to create a compound, the transfer of electrons generates an ionic bond. True False

Study this chemical reaction: ZnCl₂(aq) +2 Na(s) - Zn(s)+2 NaCl(aq) Then, write balanced half-reactions describing the oxidation and reduction that happen in this reaction.

The heat of vaporization of a substance is 5900 Joules/gram at its boiling point of 130°C. How much energy would be required to evap- orate 79000 grams of this substance? Answer in units of Joules.

Example: Nitrogen gas reactions with oxygen gas to produce nitrogen dioxide gas. At equilibrium: [nitrogen gas] = 0.45 M [oxygen gas] = 0.80 M [nitrogen dioxide] = 0.75 M Calculate the equilibrium constant.

You just got a new job at Tommy's Malt Shop! It is your job to order all the food. To make a cheese burger you need to follow this recipe: 3 Ch + 1 M + 2 B→1 Ch3MB₂ In your order one box contains 1050 pieces of Ch (cheese), 850 M (meat patties), and 1000 B (buns). a. How many total cheese burgers will you be able to make? (SHOW WORK) b. What is the limiting ingredient (s)? Why? c. What is the excess ingredient (s)? Why?

Which of the following reactions results in an increase in the entropy of the system? A) CH4(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) B) BaO(s) + CO2(g) → BaCO3(s) C) NH4CI(s) → HCl(g) + NH3(g) D) 2HCl(g) + F₂(g) → 2HF(g) + Cl₂(g) E) 4Co(s) + 3O₂(g) → 2Co₂O3 (s)

A 30-g sample of an unknown metal absorbs 29.0 J of heat, upon which the temperature of the sample increases from 24 °C to 40 °C. What is the specific heat of this metal in J/g-K? A) 0.060 B) 0.0033 C) 0.95 D) 15.5 E) 280

Arrange the following from largest to smallest atomic radius: 1. O, 2. 0²-, 3. s², 4. 0²+ Use the numbers rather than the symbols, ex. 1 2 3 4 with one digit in each blank, four blanks total.

In the following reaction, how many mL of 0.350 M magnesium bromide solution reacts with excess silver nitrate to form a 3.00 g of AgBr precipitate? (molar mass of AgBr = 187.77 g/mole) MgBr₂(aq) + 2AgNO3(aq) --> 2AgBr(s) + Mg(NO3)2(aq) 22.8 mL 45.6 mL 1.86 mL 91.3 mL none of these

Construct the expression for Kc for the following reaction. CH3COOH(aq) + H₂O(I) ⇒ CH³COO-(aq) + H³O^(aq) Drag the tiles into the numerator or denominator to form the expression.

You want to create 600. g Ca3(PO4)2 and need to know how much of each reactant to use. 2(NH4)3PO4 + 3Ca(C₂H30₂)2 -> 6NH4C₂H3O2 + Ca3(PO4)2 (S) What mass of (NH4)3PO4 is required to generate 600. g Ca3(PO4)2?

A chemist dissolves 66. mg of pure sodium hydroxide in enough water to make up 170. mL solution. Calculate the pH of the solution. (The temperature of the solution is 25 °C.) Be sure your answer has the correct number of significant digits.

Consider the equilibrium system described by the chemical reaction below. At equilibrium, a 5.0 L reaction vessel contained a mixture of 1.2 mol CH4, 2.8 mol H₂S, 0.63 mol CS2, and 0.042 mol H₂ at 93.0 °C. What are the values of Kc and Kp for the reaction at this temperature? CH4(g) + 2 H₂S(g) = CS₂(s) + 4 H₂(g) Based on the given data, set up the expression for Kc and then evaluate it. Do not combine or simplify terms. Kc =

Which of the following pairs of elements would have the most similar chemical properties? A. magnesium and aluminum B. antimony and tin C. phosphorus and sulfur D. chlorine and bromine

Because speeches are louder than normal conversations, you can practice by creating a mental image of propelling your voice to the far corners of the room pausing to breathe between phrases to have more breath keeping your head up and opening your mouth wide all of the above none of the above

Ascorbic acid (vitamin C) is a diprotic acid, H₂C6H606. Calculate [H*], pH, and [C6H6O62-] in a 0.50 M solution of ascorbic acid.