chem lab

Arrange the following aqueous solutions in order of increasing boiling point temperature (lowest to highest temperature, with 1 being the lowest and 4 being the highest): 0.20 m glucose, 0.30 m BaCl2, 0.40 m NaCl, 0.50 m Na2SO4.

0.20 is 1 0.30 is 3 0.40 is 2 0.50 is 4

A 312 g sample of a metal is heated to 344.401 °C and plunged into 200 g of water at a temperature of 49.171 °C. The final temperature of the water is 92.01 °C. Assuming water has a specific heat capacity of 4.184 J/g °C, what is the specific heat capacity of the metal sample, in J/g °C)? Assume no heat loss to the surroundings. Report your response to 3 digits after the decimal.

0.455

Predict the ideal bond angles around nitrogen in N2F2 using the molecular shape given by the VSEPR theory. Enter a number without the degree symbol.

120 n2f2 is trigonal planar

If 5.28 moles of gas are produced in an experiment and it is measured that they occupy 112 L at STP, what is the experimental molar volume of the gas? Enter your answer numerically in units of L/mol.

21.2

what is the volume indicated, to the correct number of significant figures? Provide a numerical answer, without units.

3.45

Which changes are chemical reactions? Select all that apply.

-Solid copper deposits on a piece of aluminum foil when the foil is placed in a blue copper nitrate solution. The blue color of the solution fades. -A white precipitate forms when solutions of barium nitrate and sodium sulfate are mixed. -A mixture of sugar and water bubbles when yeast is added. After several days, the sugar is gone and ethyl alcohol is found in the water. -Copper turns green upon exposure to air. -when sodium bicorbante is combined with hydrochloric acid, bubbling... -a pure copper penny forms bubbles...

-Which ion(s) is/are spectator ions in the reaction, if any, that results from combining aqueous solutions of BaI2 and Na2SO4 Select all that apply. -Identify all the spectators ions in the following reaction 2KMnO4(aq)+10FeSO4(aq)....

I-, Na+ K+, SO42-

Which of the following best expresses the net ionic equation for the reaction, if any, when aqueous solutions of copper(II) sulfate and sodium iodide are combined? (Hint: in this instance, imagine that CuI2 is insoluble) Which of the following would you expect to be nonelectrolytes when dissolved in water. MgCl2, Ch3Oh, n2

C u ( a q ) 2 + + 2 I ( a q ) − ⟶ C u I 2 ( s ) -Ch3OH and n2

What is the safety pictogram for household bleach (sodium hypochlorite solution, 5-12.5%)?

skin corrosion/burns

What is the term for the component of a solution that is the lesser quantity?

solute

The hybridization of the central nitrogen atom in the molecule N2O is

sp n2o is linear

If 0.257 g of Mg are reacted with 10.0 mL of 3 M HCl, how many moles of H2 should be produced theoretically? Enter your answer numerically in units of moles.

ans 0.0106

The reported molar absorptivity of Red Dye #3 is 2.595 L mol-1 cm-1. If a solution of Red Dye #3 displays an absorbance of 0.418 in a cuvette that is 1.15 cm in length, what is the concentration of the dye in solution? Report your response to three digits after the decimal. _____ M

ans 0.14

A student's calibration curve for Blue #1 at 635 nm yields a straight line described by the equation y = 0.34 x + 0.022. If the measured absorbance for a solution of unknown concentration of Blue #1 is 0.102, what is the concentration of the Blue #1 solution? Provide your response to three digits after the decimal.

ans 0.235 0.102=0.34x+0.022 x=0.235

Sam records the mass of his evaporating dish as 8.875 g. He records the mass of the evaporating dish and the sample of hydrate as 19.452 g. After heating the sample in the evaporating dish to constant weight, the mass of them combined is 11.972 g. How many moles of water were removed from the sample by the heating process? Report your answer with three digits after the decimal.

ans 0.415

A stock solution of Blue #1 has a concentration of 4.565 M. 1 mL of this solution is diluted with 8 mL water. What is the concentration of the resulting solution? Provide your response to 3 significant figures.

ans 0.507

A student collects hydrogen gas over water in a graduated cylinder. If the student measures that the total pressure inside the graduated cylinder is 0.931 atm and the experiment was performed at 25C, what is the pressure of hydrogen gas? Enter your answer numerically in units of atm.

ans 0.9

If you have an aqueous solution that is 16.8 % Na3PO4 by mass, what is the molality of Na3PO4 in the solution? Enter your answer in units of molality to three significant figures.

ans 1.23

Jason measures three values of density for his unknown. The values he obtains are: 1.217 g/mL 1.786 g/mL 1.135 g/mL What is the average of his three measurements? Express your response to three digits after the decimal.

ans 1.379 add all numbers and divide by 3 to get average.

A titration is performed as follows: 10.338 mL of Fe2+ solution of unknown concentration is charged into a 100 mL beaker 45 mL of deionized water is added the solution is titrated with 0.878 M Ce4+ solution the equivalence point is reached after 16.247 mL of Ce4+ solution is added What is the concentration of the Fe2+ solution? Report your response to three digits after the decimal.

ans 1.381

Examine the second derivative plot shown below. At what approximate added volume of titrant does the equivalence point occur? Enter your answer numerically in units of mL.

ans 10.5 the answer is where the line passes

Jill creates a standard curve of mass vs volume for a series of solutions. Her curve is shown below. She is provided with a solution of unknown concentration (mass %). If the density of the unknown solution is 1.779 g/mL, what is the concentration of the solution, expressed as mass %? Provide a numerical response, without units, to 3 digits after the decimal

ans 103.026 1.779=0.0076x+0.996 x=103.026 (0.0076x+0.996 is given in graph)

If the energy of a photon is 1.32 × 10-18 J, what is its wavelength in nm? Enter a whole number to complete the expression: _____ nm

ans 151

George determines the mass of his evaporating dish to be 2.22 g. He adds a solid sample to the evaporating dish, and the mass of them combined is 20.91 g. What must be the mass of his solid sample? Express your response to three digits after the decimal.

ans 18.69

Consider that you prepared a solution by mixing 0.25 g solute with 8.12 g of solvent. If you measured that the solution had a molality of 0.166 m, what is the molar mass of the solute? Express your answer numerically to three significant figures.

ans 185.2

An anhydrous (water removed) salt has a formula mass of 225.773 g/mol. If the hydrated version of the salt has 5 mol of water associated with it, what is the mass % of water in the hydrated salt? Report your answer to three digits after the decimal.

ans 28.513

A student is told the theoretical mass % water in her sample is 69.613 %. She obtains an experimental value of 48.241 % when she performs the lab activity. What is her % error? Report your answer to three digits after the decimal

ans 30.701

Melanie obtains a value of 2.146 g/mL for the density of her unknown solution. The actual density of the solution is 1.571 g/mL. What is the % error of Melanie's measurement? Express your response to two digits after the decimal.

ans 36.6 Percent error= (2.146-1.571)/1.571 x 100 0.575/1.571 x 100 0.366009 x 100= 36.6

The concentration of dye in Solution A is 27.78 M. You have 13 mL of water at your disposal to make the dilutions. The solution is diluted twice, to make Solutions B and C. In the first dilution, 5 parts of Solution A is diluted with 12 parts water to make Solution B. In the second dilution, 4 parts of Solution B is diluted with 4 parts water to make Solution C. What is the concentration of dye in Solution C? Provide your response to three digits after the decimal.

ans 4.085

A student measures the pressure, volume, and temperature of a gas in the laboratory and records the following data: P = 0.41 atm, V = 112 mL, T = 300 K Based on this information, what would be the volume of the gas at STP? Enter your answer to three significant figures in units of mL.

ans 41.8

Suppose you are investigating the reaction: M(s) + 2 HCl(aq) → MCl2(aq) + H2(g). You weigh out a 0.212 gram piece of metal and combine it with 68.7 mL of 1.00 M HCl in a coffee-cup calorimeter. If the molar mass of the metal is 53.13 g/mol, and you measure that the reaction absorbed 167 J of heat, what is the enthalpy of this reaction in kJ per mole of limiting reactant? Enter your answer numerically to three significant figures in units of kJ/mol.

ans 41.8

Examine the sample ORP output below. At what approximate added volume of titrant does the equivalence point occur? Enter your answer numerically.

ans 6.6 answer will be wherever the graph suddenly spikes.

Consider that you prepared a solution by dissolving 1.61 mL of an unknown organic substance (d = 0.953 g/mL) into 26.7 mL of cyclohexane (d = 0.774 g/mL). What is the mass percent of the unknown in the solution? Enter your answer in units of mass percent to three significant figures.

ans 6.9

A student heats a sample of hydrate once, and the mass of the sample and the evaporating dish is 17.86 g. After a second heating cycle, the mass of the sample and the dish is 14.78 g. The student stops the heat/cool/weigh cycle after the second time. If the original mass of the evaporating dish and the hydrate was 21.71 g, and the mass of the evaporating dish alone was 1.315 g, what is the mass of water removed from the sample by heating? Provide your response to three digits after the decimal.

ans 6.93

What would be the freezing point of a solution that has a molality of 1.752 m which was prepared by dissolving biphenyl (C12H10) into naphthalene? Relevant information is provided below. Provide your response to three digits after the decimal. 80.6, 6.9, 218, --

ans 68.511

A student performs an experiment where gas is collected over water in an upside down graduated cylinder. If the atmospheric pressure is 742 mmHg and the level of water in the graduated cylinder is 13.1 cm higher than the level of the water exposed to the atmosphere, what is the total pressure of gases inside the graduated cylinder? Enter your answer numerically in units of mmHg.

ans 732.4

Standard heats of formation for reactants and products in the reaction below are provided. 2 HA(aq) + MX2(aq) → MA2(aq) + 2 HX(l) -98.178, 329.723, 343.704, 443.367 What is the standard enthalpy of reaction, in kJ? Report your answer to three digits after the decimal.

ans 756.139 q2 in image

A student measures the absorbance of a sample of red dye #3 using a spectrophotometer. If the absorbance is measured as 0.692, what is the concentration of red dye #3 in the sample? Enter your answer in units of micromolar to three significant figures.

ans 8.7

Select the best Lewis structure for P2I4.

ans A

You will need to generate a set of graphs to answer this question. Concentration vs time data for the following decomposition reaction was collected at 300 K. The data is shown in the table below. What is the rate constant for the reaction at this temperature (in units of min-1)? H2O2(aq) → H2O(l) + 1/2 O2(g)

ans Between 0.0012 and 0.0014 i answered 0.0013 excel is used for this one so just guess.

Which one of the following sets of units is appropriate for a second-order rate constant?

ans L mol-1s-1 for third order its L2mol-2s-1 for zero order its molL-1s-1

You determine that the specific heat capacity of your unknown metal is 0.524 J/goC. What is the identity of the metal?

ans Ti

A student makes three plots of their data and finds that a plot of [A] vs t is linear, a plot of ln[A] vs t is non-linear, and a plot of 1/[A] vs t is non-linear. What is the rate law of the reaction?

ans rate=k

A student obtains the following data: Mass of empty, dry graduated cylinder: 27.186 g Volume added of NaCl solution: 1.429 mL Mass of graduated cylinder + NaCl solution: 45.528 g What is the density of the solution? Express your answer to 3 digits after the decimal.

ans. 12.835 (Q3 on image)

What is the equation of a line, in slope-intercept form, that connects the following two data points? (5.0, 1300) (6.0, -850) Enter your answer by filling in the following blanks. Enter each of your answers as whole numbers without any rounding.

ans. y=-2150x+12050 use mathaway. input (5.0,1300),(6.0,-850). use find the slope for the first value. then use find the x and y intercept to find the second value (y intercept)

CuSO4 absorbs light strongly at a wavelength of 635 nm. Consider that you measure the initial intensity of light, Io, entering the solution at 635 nm, and the intensity of light passing through the solution, I, at 635 nm. Sample 1: 0.400 M CuSO4 Sample 2: 0.200 M CuSO4 Which of the following statements is true?

ans: The percent transmittance of light, %T, will be lower for Sample 1 compared to Sample 2.

A solution of citric acid of unknown concentration, prepared in deionized water, is titrated with standardized sodium hydroxide solution, also in deionized water. A few drops of phenolphthalein is added to visualize the pH change. Phenolphthalein changes color from colorless to pink between pH of 7 - 9. What is the titrant in this titration? What is the analyte in this titration?

answers: titrant is sodium hydroxide. analyte is citric acid

Which one of the following molecules is nonpolar?

NH3 OF2 CH3Cl H2O Becl2

A coffee cup calorimeter is prepared, containing 100.000 g of water (specific heat capacity = 4.184 J/g K) at initial temperature 80.000 C. A salt weighing 6.13 g is quickly added. The salt has a molar mass of 488.496 g/mol. The final temperature of the solution is 52.591 C. Assume no heat loss to the surroundings. Assume the specific heat capacity of the solution is equal to that of pure water, and that the mass of the solution is equal to the mass of the solid plus the mass of water in the calorimeter. What is the molar heat of solution for the salt, in kJ/mol? Report your answer to three digits after the decimal.

970.494

In which one of the following is the best Lewis structure a resonance structure?

CO2 ClO3- COCl2 NO2+ HCN