General Questions and Answers

The graduated cylinder was found to an average of 9.765 ± 0.170 mL in measuring 10-mL portions. What are the percent error and percent accuracy of the graduated cylinder?

Experiment 5: Ionic Reactions in Aqueous Solutions a) lonic compounds containing chromate (CrO42-) ions are insoluble except when the cations are in group 1A or ammonium (NH4+). b) In general acid turns blue litmus paper from blue to red. c) When base reacts with acid, gas is evolved. d) When HCl(aq) is poured on the CaCO3(s) the solution gets cooler. e) If you want to test a substance is a base, a red litmus paper would give the best result.

Experiment 4: Limiting Reagent and Percent Yield The amount of 2.00 g of NaCl and 4.00 g of AgNO3 are used in this experiment. According to the chemical equation NaCl(aq) + AgNO3(aq) AgCl(s) + NaNO3(aq) a) Which one of the two compounds is the limiting reagent? - b) What is the theoretical yield (to 2 decimal places in grams) of the previous question? c) If only 3.12 g of AgCl is collected from the experiment described in previous question, what is the percent yield (2 decimal places) of the experiment?

"Synthesis gas" is a mixture of carbon monoxide and water vapor. At high temperature synthesis gas will form carbon dioxide and hydrogen, and in fact this reaction is one of the ways hydrogen is made industrially. A chemical engineer studying this reaction fills a 1.5 L flask with 1.3 atm of carbon monoxide gas and 4.1 atm of water vapor. When the mixture has come to equilibrium she determines that it contains 0.70 atm of carbon monoxide gas, 3.5 atm of water vapor and 0.60 atm of carbon dioxide. The engineer then adds another 1.4 atm of water, and allows the mixture to come to equilibrium again. Calculate the pressure of hydrogen after equilibrium is reached the second time. Round your answer to 2 significant digits.

Calculate the volume in milliliters of a 0.677 mol/L sodium thiosulfate solution that contains 25.0 g of sodium thiosulfate (Na₂S₂O3). Be sure your answer has the correct number of significant digits. mL x10

Give the empirical formula of a compound that is composed of 91.75 % N and 8.25 % H. Calculate the moles of N= Calculate the moles of H= mol N What number must you multiply each ratio by in order to convert all decimals to whole numbers and get the empirical formula? N mol H Calculate the empirical formula. Put only whole numbers in the blanks. H

In the mass spectrum of Br2, the two isotopes of bromine (79Br and 81Br) are roughly equally distributed. However, the Br₂ fragments shows three distinct lines of roughly of 1:2:1 ratio at masses of 158, 160, and 162. Which one of the following would be the best explanation? None of the explanation is correct. When 79Br combined with 81Br, equal amount of two different mass are added. When 79Br or 81Br form Br₂ by itself, only one isotope mass is involve. Thus the amount of two different mass combined are twice as much as only one mass combined with itself. Both explanations are correct. When the two isotopes combined, the amount of 79Br79Br, 79Br81 Br, 81 Br79 Br, and 81Br81 Br all have the same amount, since 79Br81Br and 81 Br79Br have the same mass, they appear on the same line. Thus the ratio of mass 160 are twice as those of 158 and 162.

What is the mass percent of Hy in Hy(NO₂)3? Hy is a hypothetical element with a mass of 18 g/mol. 16% 12% 14% 10% 15% 11% 13 % 17%

How many grams of titanium(IV) hydroxide, Ti(OH), will contain 3.4 x 1025 hydroxide ions? Work through the steps to get to the final answer. a) From the number of hydroxide ions given, calculate how many moles of hydroxide ions are present? b) How many moles of titanium(IV) hydroxide are present? c) Calculate the molar mass of titanium(IV) hydroxide. d) Calculate the number of grams of titanium(IV) hydroxide. mol g/mol g mol

How many moles of compound would be in 8.50 g Ar(CN)2, if this compound could form? 10.8 8.50 0.0924 0.169 69.9 0.0298 782

An unknown hydrate, AC XH₂O, has a mass of 1.000 g before heating, and 0.738 g after heating. What is the experimental percentage of water in the hydrate? If the anhydrous compound (AC) has a molar mass of 101 g/mol, what is the water of crystallization (X) and the formula for the hydrate (AC XH₂O)? Water of crystallization Formula of hydrate AC H₂0

When 3.89 g of bismuth oxide (molar mass=465.96 g/ml) reacts with excess carbon to form 2.83 g of bismuth metal (molar mass=208.98 g/mol) according to the equation: Bi2O3(s) + 3 C(s)- 2 Bi(s) + 3 CO(g) What is the percent yield of the reaction?

Calculate the volume in milliliters of a 6.2 mol/L silver nitrate solution that contains 75.0 mmol of silver nitrate (AgNO3). Be sure your answer has the correct number of significant digits.

Enter the chemical formula of a binary molecular compound of hydrogen and a Group 7A element that can reasonably be expected to be less acidic in aqueous solution than HBr, e.g. have a smaller &.

A gas is contained in a cylinder with a volume of 25 mL at a temperature of 46°C and a pressure of 0.54 atm. The gas is then compressed to a volume of 3.5 mL while heated to 100°C. What is the new pressure inside the cylinder? Show all work and include all units

When 3.52 g of bismuth oxide (molar mass = 465.96 g/ml) reacts with excess carbon to form 2.90 g of bismuth metal (molar mass = 208.98 g/mol) according to the equation: Bi₂O3(s) + 3 C(s) → 2 Bi(s) + 3 CO(g) What is the percent yield of the reaction? (Answer to 1 decimal place)

A chemist adds 370.0 mL of a 0.38 mol/L copper(II) sulfate (CuSO4) solution to a reaction flask. Calculate the millimoles of copper(II) sulfate the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

A chemist adds 1.75 L of a 11.4 mol/L silver perchlorate (AgC104) solution to a reaction flask. Calculate the millimoles of silver perchlorate the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

Suppose a certain material has a specific heat of 0.802 J/g°C. If 5.51 kJ of heat is applied to 405.4 g of the material at 25.6°C, what is the final temperature (in °C) of the material? (Answer to 1 decimal place)

A chemist adds 60.0 mL of a 7.5 × 10 -4 mol/L magnesium fluoride (MgF₂) solution to a reaction flask. Calculate the micromoles of magnesium fluoride the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

FOR PRACTICE 8.5 On the basis of periodic trends, choose the larger atom in each pair (if possible): (a) Sn or I (b) Ge or Po (c) Cror W (d) For Se FOR MORE PRACTICE 8.5 Arrange the elements in order of decreasing radius: S, Ca, F, Rb, Si.

What is the mass in grams of a single calcium atom? (hint: start with 1 atom Ca and do 2 dimensional analysis steps) Format for the answer is x 10 exponent __x 10__ Give value to four significant figures.

A 55.1 mL sample of a 0.102 M potassium sulfate solution is mixed with 39.0 mL of a 0.112 M lead (II) acetate solution and this precipitation reaction occurs: K₂SO4 (aq) + Pb(C₂H302)2 (aq) 2 KC 2H3O2 (aq) + PbSO4 (s) The solid PbSO4 (molar mass = 303.26 g/mol) is collected, dried, and found to have a mass of 1.04 g. Determine the theoretical yield in grams. (Answer to 2 decimal places)

A tank of nitrous oxide (N₂O) has a pressure of 840 torr at 115 °C. What is the temperature in degrees Celsius (°C) if the pressure decreases to 535 torr at constant volume (V) and amount (n)? K = °C + 273 P₁V₁/T₁ = P2V2/T₂

Graph the polynomial function f(x) = x(3-x)(6-x) using parts (a) through (e). (a) Determine the end behavior of the graph of the function. The graph of f behaves like y= for large values of [x].

You will need a handout of the periodic table. a. On your periodic table, clearly label the alkali metals, the alkaline earth metals, the halogens, and the noble gases. (If you wish, you may color them and provide b. Label the main group elements, the transition elements, and the lanthanides and a color key at the top.) actinides.

Determine the enthalpy of reaction in kJ for HCI(g) + NaNO₂(s) → HNO₂(1) + NaCl(s) Given the following thermochemical equations: 2NaCl(s) + H₂O(1)→ 2HCI(g) + Na₂O(s) AH° = -507.1 kJ NO(g) + NO₂(g) + Na₂O(s) → 2NaNO₂ (s) AH° = -427.0 kJ NO(g) + NO₂(g) → N₂O(g) + O₂(g) AH° = -43.01 kJ 2HNO₂(1)→ N₂O(g) + O₂(g) + H₂O(1) AH° = 34.02 kJ (Answer to 1 decimal place)

How many moles of oxygen are in 1mole of Al2(SO4)3? _____ mol O

Calculate the molar mass of HNO3 and record to the hundredths place. _________g/mol Use the Periodic Table values given in this assignment. Other values will be counted as incorrect.

An atom is found to have succesive ionization energies of 1000, 2251, 3361, 4564, 7013, 8495, and 27106 kJ/mol. Which of the following could be the atom? A. Na B. Mg C. Al D. Si E.P F. S G. CI H. Ar

Robert was able to travel 218.0 miles in 5.000 hours and used 36 liters of gasoline. What was Robert's speed in feet per second? (5,280 ft 1 mi) Report your answer using four significant figures. Provide your answer below: = ft/s

If the solution that you decanted from the Cu at the end of this part was still slightly blue, would you expect that to result in an incorrectly high (more copper than expected) or an incorrectly low (less copper than expected) amount of copper recovered at the end of the sequence? Briefly explain.

Draw the Lewis structure of SeOF2 (with minimized formal charges) and then determine the ideal bonding angle(s) of the central atom. + Click to draw a new structure A) 90° and 120⁰ B) 109.5⁰ C) 60° D) 45° E) 90°

A scientist measures several 100 g masses and finds the results: 99.9 g, 99.9 g, and 100 g. What is true about the results? Select the correct answer below: They are accurate. They are precise. They are both accurate and precise. They are neither accurate nor precise.

Consider the ionization values for elementy: 1st IE: 786.5 kJ/mol 2nd IE: 1577.1 kJ/mol 3rd IE: 3231.4 kJ/mol 4th IE: 4355.5 kJ/mol 5th IE: 16,090.6 How many valence electrons does element y contain and what group is it located within?

What is the number of moles of Ba(NO3)2 in 135 g Ba(NO3)2? ----- mol Ba(NO3)2

Why does K have a larger atomic radius than Na? The valence electrons in Na feel a stornger effective nuclear charge than those in K. The valence electrons in K feel a stronger effective nuclear charge than those in Na. OK is lower down the group than Na. The valence electrons in Na and K feel a similar Zeff. Those in K are in a higher energy level. The valence electrons in Na and K feel a similar Zeff. Those in Na are in a higher energy level.

Which of the following statements is true about energy quantization at the atomic level? Electrons in the outermost orbits are the most stable. Electrons in all the orbits around the nucleus have the same amount of energy. Electrons in the orbit closest to the nucleus have the least amount of energy. Electrons absorb or release the same amount of energy independent of the energy levels.

A lattice dissociation enthalpy (lattice energy) is A) the energy required to break a chemical bond. B) the amount of energy that must be supplied to break an ionic solid into its individual gaseous ions. C) the difference in ionization energy and electron affinity of the anion and cation. D) the energy required to convert a substance from a solid to a gaseous state.

Which option would be an appropriate model of nuclear fusion? mashing two marshmallows together adding a drop of water to a glass of water putting a puzzle together sewing one piece of fabric to another

(8 pts) In an experiment to determine how to make sulfur trioxide, a chemist combines 32.0 g of sulfur with 50.0 g of oxygen. She finds that she made 80.0 g of sulfur trioxide and had 2.0 g of leftover oxygen. How would the chemist make 100.0 g of sulfur trioxide so that she has no leftovers?

Which of the following statements is correct for precipitation reaction? All the products must be insoluble. At least one of the products is insoluble. All the reactants must be insoluble. At least one of the reactants must be insoluble.

Draw the Lewis structure of H₂CS and then determine its electron domain and molecular geometries. A) planar / tetrahedral B) trigonal planar / linear C) trigonal / trigonal planar D) trigonal planar / trigonal planar E) planar / planar

Which of the following products are formed when copper (II) sulfate is treated with hydrogen sulfide gas? Copper (II) sulfide and sulfuric acid Copper (1) sulfide and sulfuric acid Copper (1) sulfide, water and sulfur dioxide Copper (II) sulfide, water and sulfur dioxide

Now that we have put a coefficient of 2 in front of Na3PO4, what coefficient should go in front of NaCl to balance sodium (Na)? 2Na3PO4 + MgCl2 →Mg3(PO4)2+?NaCl

The following equation is not balanced: Na3PO4 + MgCl2 →Mg3 (PO4)2 + NaCl Notice that "PO4" appears in two different places in this chemical equation. PO is a polyatomic ion called phosphate. What number should be placed in front of Na3PO4 to give the same total number of phosphate ions on each side of the equation? ?Na3PO4 + MgCl2 →Mg3 (PO4)2 + NaCl

18.01% C, 2.27% H, and 79.76% Cl

76.0% Zn and 24.0% P Express your answer as a chemical formula. A chemical reaction does not occur for this question.

3. Section Outline: Atomic Mass (Pick 2) (1 Point) All atoms of the same element have approximately the same mass. Mendeleev's table showed which elements would react with chlorine. The average atomic mass is often expressed as a decimal number. Mendeleev left gaps in the periodic table for undiscovered elements.

An atom (X) has the following fictitious succesive ionization energies: 745, 1685, 2541, 4425, 7185, 10752, and 27896 kJ/mol. What ion would you expect atom X to make? A.X+ B.X2- C.X D.X³- E. X3+ F. X2+