Chem lab Final Review
titration problem equation
M1V1=M2V2
What is the name of the compound with the formula Ca(OH)2?
calcium hydroxide
After heating the unknown mixture, the mass of the sample is expected to _____ .
decrease
The specific heat of water is 4.184 J/g•°C. What amount of heat, in joules, is required to raise the temperature of 65.52 grams of water from 25.5°C to 46.6°C? Report your answer with 3 significant figures.
5.78e3
A 2.43 gram sample of a KCl and KClO3 mixture was found to contain 0.01091 mol of KClO3. What is the percent by mass of KClO3 in the original mixture? Report your answer with three significant figures.
55.0 %
When the equation is properly balanced, the coefficient of H2 is _____. ___ Fe + ___ H2S04 → ___ Fe2(SO4)3 + ___ H2
__2_ Fe + ___3 H2S04 → ___ Fe2(SO4)3 + __3_ H2
A student performs a titration in order to determine the concentration of a hydrochloric acid solution. Early in the procedure, the flask is not placed directly under the buret and a small amount of the titrant, KOH, drains down the outside of the flask. How will this error affect the calculated value of the HCl concentration?
calculated value< actual value
In the titration of a monoprotic acid with a monoprotic base, the point at which the same number of moles of acid and base have been added is called the
equivalence point
Elements A and B are in the same row of the periodic table. Element A is closer to the right side of the table than B. Element A likely has a larger atomic radius.
disagree
What is the name of the compound with the formula MgI2?
magnesium iodide
Which molecule or ion has 34 valence electrons?
oxalate anion, (C2O4)2-
During the decomposition of KClO3, 5.09 grams of oxygen gas are created. How many moles of KClO3 reacted? Report your answer with 3 significant figures. 2 KClO3 → 2 KCl + 3 O2
.106 mol KCLO3
What is the concentration of a solution of a monoprotic acid (i.e., HA) which required 19.25 mL of 0.0965 M KOH to titrate 15.00 mL of the acid solution? Report the answer with the correct number of significant figures.
.124 M
During the decomposition of KClO3, 9.18 grams of oxygen gas are created. How many moles of KClO3 reacted? Report your answer with 3 significant figures. 2 KClO3 → 2 KCl + 3 O2
0.191
The composition of a mixture of potassium chlorate and potassium chloride is to be determined. A 9.87 gram sample of the mixture is heated until the creation of oxygen gas stops. If the sample mass after heating is 7.04 grams, what is the percent by mass of potassium chlorate in the mixture? Report your answer with 3 significant figures.
-9.87-7.04 = 2.83g evolved oxgen f-ind mol of O2 first then find mol of KClO3 -set up percent composition using original mass 9.87g 73.2 %
What is the concentration of a solution of a diprotic acid (i.e., H2A) which required 19.25 mL of 0.0965 M KOH to titrate 15.00 mL of the acid solution? Report the answer with the correct number of significant figures.
0.062 ml
In the replacement reaction of magnesium nitrate with tin, how many grams of tin(IV) nitrate would be produced if 59.5 mg of magnesium nitrate? Report your answer with 3 significant figures. 2 Mg(NO3)2 + Sn → Sn(NO3)4 + 2 Mg
0.0735 or 7.35 e-2
If 258.5 Joules of heat are added to 22.22 grams of a liquid, raising the temperature of the liquid from 25.5°C to 35.1°C, what is the specific heat capacity of the liquid with units of J/g•°C? Report your answer with 3 significant figures.
1.21
When heated, iron(III) hydroxide decomposes according to the equation below. When balanced, the coefficient of iron(III) hydroxide is ____. ___ Fe(OH)3 (s) → ___ Fe2O3 (s) + ___ H2O (g)
2
A 29.37 mL portion of a 0.4 M solution of hydrochloric acid, a monoprotic acid, is to be titrated with a standarized 0.401 M solution of KOH. What is the expected volume in milliliters of the KOH solution needed to reach the phenolphthalein end point? Report your answer with a precision of two decimal places.
29.30 ml
Which of the following is the correctly balanced equation representing the reaction taking place in this experiment, the decomposition of potassium chlorate to form a solid and a gas?
2KClO3---> 2KCl + 3O2
A 2.51 gram sample of a KCl and KClO3 mixture was found to contain 0.0125 mol of KClO3. What is the percent by mass of KClO3 in the original mixture? Report your answer with three significant figures.
61.1%
Calculate the volume in milliliters of 0.335 M KOH necessary to titrate 0.0214 moles of acetic acid (HOAc, HC2H3O2) to a phenolphthalein end-point. Report the answer with a precision of two decimal places.
63.88
In the replacement reaction of magnesium nitrate with tin, how many grams of magnesium would be produced if 50.2 mg of magnesium nitrate? Report your answer with 3 significant figures. 2 Mg(NO3)2 + Sn → Sn(NO3)4 + 2 Mg
8.22e-3
Calculate the volume in milliliters of 0.321 M KOH necessary to titrate 0.0268 moles of acetic acid (HOAc, HC2H3O2) to a phenolphthalein end-point. Report the answer with a precision of two decimal places.
83.48 ml
What is meant by "tare weight of the evaporating dish" in the last step of the procedure?
Empty evaporating dish
When the equation is properly balanced, the coefficient of FeCl3 is _____. ___ Fe + ___ HCl → ___ FeCl3 + ___ H2
__2_ Fe + __6_ HCl → ___2 FeCl3 + 3___ H2
What is the name of the compound with the formula Ba(NO3)2?
barium nitrate
What is the name of the compound with the formula CO3?
carbon trioxide
In this experiment, we are able to indirectly determine the heat lost by a hot object by determining the heat gained by a cooler liquid. This is possible because of which thermodynamic relationship
qlost=-qgained
An acid with molar mass 84.48 g/mol is titrated with 0.650 M KOH. What volume of KOH solution is needed to titrate 1.70 grams of the acid to the equivalence point.
see Gen Chem notes 596
Precise determination of the concentration of a solution is called _____.
standardization
Which molecule or ion has 18 valence electrons?
sulfur dioxide, SO2
In this experiment, the starting temperature of the water receiving the heat from the metal is _____, and the starting temperature of the metal is _____.
the temperature of the water inside the calorimeter; the temperature of the boiling water start temp of metal= temp of boiling water
A 2.38 gram sample of a KCl and KClO3 mixture was found to contain 0.01344 mol of KClO3. What is the percent by mass of KClO3 in the original mixture? Report your answer with three significant figures.
-KEYWORD IS PERCENT -69.2%
Which of the following are decomposition reactions? Choose all that apply.
-PbCO3(s)--> PbO + CO2 -2H202--> 2H2O + O2
Which molecule or ion has 16 valence electrons?
-count group #s carbon dioxide, CO2
What is the concentration of a sulfuric acid solution (a diprotic acid, H2SO4) which requires 27.95 mL of 0.124 M NaOH solution to titrate 25.00 mL of the acidic solution?
-draw/balance equation first .0693 M
In this experiment, suppose that 2.7 grams of copper are recovered after beginning with 3.53 grams. Calculate the percent recovery. Report your answer with three significant figures.
-mass recovered/actual massX 100 -76.48
What change(s) do you expect to observe over the course of the reaction? Choose all that apply- Experiment 8 prelab
-need help
Calculate the volume in milliliters of 0.201 M KOH necessary to titrate 25.98 mL of 0.288 M diprotic sulfuric acid, H2SO4, to a phenolphthalein end-point. Report the answer to a precision of 2 decimal places.
-need help -see additional problems for titration pdf
The concentration of an unknown acid solution with general formula H3A is to be determined by titration with a 0.850 M KOH solution. Determine the concentration of the acid solution given that 38.34 mL of KOH solution were needed to fully neutralize 15.00 mL of the acid solution.
0.724
Use the following data to determine the percent recovery of copper. Report your answer with three significant figures. starting mass of copper:1.24 grams tare weight of evaporating dish:26.47 grams mass of evaporating dish and recovered copper:27.08 grams
27.08-26.47 grams recovered divide by 1.24 X 100
A 37.48 gram sample of copper (specific heat, 0.385 J/g•°C) with an initial temperature of 99.6°C is added to a calorimeter containing 175.89 grams of water (specific heat, 4.184 J/g•°C) at 25.7°C. What is the final temperature of the metal? Report your answer with 3 significant figures.
28.9
When heated, iron(III) hydroxide decomposes according to the equation below. When balanced, the coefficient of water is ____. ___ Fe(OH)3 (s) → ___ Fe2O3 (s) + ___ H2O (g)
3
Metal carbonates decompose to form metal oxides and carbon dioxide. An experiment was done to determine the composition of a mixture of sodium chloride and sodium carbonate. A sample of the mixture with a mass of 5.98 grams was heated until gas production stopped. After the reaction, the sample had a mass of 4.49 grams. Assuming that sodium chloride does not react and that the decrease in mass was due to the creation of CO2 gas, what wass the mass of Na2CO3 in the sample? Report your answer with three significant figures. Na2CO3 → Na2O + CO2
3.59 g (similar to evolved oxygen problem but not quite the same)
Calculate the volume in liters of 0.533 M KOH necessary to titrate 0.017 moles of hydrochloric acid, HCl, to a phenolphthalein end-point. Report the answer with three significant figures.
31.9 ml
A 19.77 mL portion of a 0.381 M solution of acetic acid, a monoprotic acid, is to be titrated with a 0.153 M solution of KOH. What is the expected volume in millileters of the KOH solution needed to reach the phenolphthalein end point? Report your answer with a precision of two decimal places.
49.23 ml
A piece of iron (specific heat, 0.444 J/g•°C) is added to 101.98 grams of water (specific heat, 4.184 J/g•°C) in a calorimeter. The water was initially at a temperature of 27.4°C and the iron was initially at 116.5°C. If the final temperature of the system is 34.7°C, what is the mass of the iron? Report your answer with 3 significant figures.
85.7
What is the name of the compound with the formula Al2(SO4)3?
Aluminium sulfate
This experiment involves a decomposition reaction. Which of the follow is true of a decomposition reaction?
a single compound becomes multiple compounds or elements
Which molecule or ion has 24 valence electrons?
acetate anion, (C2H3O2)-
A hot solid is added to a cooler liquid and no reaction takes place, they are simply mixed. The final temperature will
always be between two initial temperatures
A student performed titration to find the concentration of acetic acid. Titrant was sodium hydroxide. He went beyond the indicator color change by adding too much titrant. How will his experimental error affect the calculated value for the concentration of unknown acetic acid?
calculated value > actual value
Is the decomposition of KClO3 a physical or chemical change?
chemical
The color of phenolphthalein changes from __________ to __________ by addition of a base solution as one reaches the neutralization point.
colorless to pink
of the compound with the formula CuSO4?
copper (II) sulfate -remember transition metals prefixes
An endothermic reaction is carried out in a calorimeter. Is the temperature of the water expected to increase, decrease, or stay the same?
decrease
Elements A and B are in the same column of the periodic table. Element A is closer to the top of the table than B. Element A likely has a smaller electronegativity.
disagree
Elements A and B are in the same row of the periodic table. Element A is closer to the left side of the table than B. Element A likely has a smaller atomic radius.
disagree
What is the name of the compound with the formula S2F4?
disulfur tetrafluoride
Classify the reaction represented by the equation BaCl2 + Na2SO4 → BaSO4 + 2 NaCl
double replacement double displacement
The point in a titration at which the indicator changes and the addition of titrant is stopped is called the _____
end point
Which one of the following is a correct expression for the concentration term "molarity"?
mole solute/L solution
What change(s) do you expect to observe over the course of the reaction? Choose all that apply.
need help- experiment 8 prelab
What is the name of the compound with the formula NaF?
sodium fluoride
3 out of 3 points A sample of metal pellets is weighed, heated and then added to a calorimeter containing room temperature water. After adding the majority of the metal sample to the calorimeter, it is discovered that some of the metal was not added and has since cooled. If the cooled portion of metal is now added to the calorimeter and the experiment continues, how will the calculated value of the specific heat be affected?
the calculated value of the specific heat will be lower than it should be
If the lid of the calorimeter is not put in place after the hot metal is added. How will this affect the final temperature of the system?
the final temperature will be lowered
How would spilling some of the reaction mixture after weighing affect the calculated KClO3-to-KCl ratio?
the ratio would be too high in KClO3
Four materials and their specific heats are listed below. If samples of each material having the same mass are initially at a temperature of 25°C, which material requires the largest amount of heat to raise its temperature to 35°C?
water (4.184 J/gc) the specific heat of metals is less than than water. Water takes longer to heat up, so it requires the largest amount of heat