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Chemistry end of chapter exercises

Under what circumstances, if any, does a sample of solid AgCl completely dissolve in pure water?

when the amount of solid is so small that a saturated solution is not produced

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Explain why the addition of NH 3 or HNO 3 to a saturated solution of Ag 2 CO 3 in contact with solid Ag 2 CO 3 increases the solubility of the solid.

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Calculate the cadmium ion concentration, [Cd 2+ ], in a solution prepared by mixing 0.100 L of 0.0100 M Cd(NO 3 ) 2 with 1.150 L of 0.100 NH 3 ( aq ).

8 × 10 –5 M

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Explain why addition of NH 3 or HNO 3 to a saturated solution of Cu(OH) 2 in contact with solid Cu(OH) 2 increases the solubility of the solid.

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Sometimes equilibria for complex ions are described in terms of dissociation constants, K d . For the complex ion AlF 6 3− the dissociation reaction is:

AlF 6 3− Al 3+ + 6 F and K d = [ Al 3+ ] [ F ] 6 [ AlF 6 3− ] = 2 × 10 24

Calculate the value of the formation constant, K f , for AlF 6 3− .

5 × 10 23

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Using the value of the formation constant for the complex ion Co ( NH 3 ) 6 2+ , calculate the dissociation constant.

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Using the dissociation constant, K d = 7.8 × 10 –18 , calculate the equilibrium concentrations of Cd 2+ and CN in a 0.250- M solution of Cd ( CN ) 4 2− .


This table has two main columns and three rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ) and Equilibrium ( M ). The second column has the header, “[ C d ( C N ) subscript 4 to the second power superscript negative sign ] [ C N superscript negative sign ] [ C d to the second power superscript positive sign ].” Under the second column is a subgroup of two rows and three columns. The first column contains the following: 0.250 and 0.250 minus x. The second column contains the following: 0 and 4 x. The third column contains the following: 0 and x.
[Cd 2+ ] = 9.5 × 10 –5 M ; [CN ] = 3.8 × 10 –4 M

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Using the dissociation constant, K d = 3.4 × 10 –15 , calculate the equilibrium concentrations of Zn 2+ and OH in a 0.0465- M solution of Zn ( OH ) 4 2− .

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Using the dissociation constant, K d = 2.2 × 10 –34 , calculate the equilibrium concentrations of Co 3+ and NH 3 in a 0.500- M solution of Co ( NH 3 ) 6 3+ .

[Co 3+ ] = 3.0 × 10 –6 M ; [NH 3 ] = 1.8 × 10 –5 M

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Using the dissociation constant, K d = 1 × 10 –44 , calculate the equilibrium concentrations of Fe 3+ and CN in a 0.333 M solution of Fe ( CN ) 6 3− .

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Calculate the mass of potassium cyanide ion that must be added to 100 mL of solution to dissolve 2.0 × 10 –2 mol of silver cyanide, AgCN.

1.3 g

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Calculate the minimum concentration of ammonia needed in 1.0 L of solution to dissolve 3.0 × 10 –3 mol of silver bromide.

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A roll of 35-mm black and white photographic film contains about 0.27 g of unexposed AgBr before developing. What mass of Na 2 S 2 O 3 ·5H 2 O (sodium thiosulfate pentahydrate or hypo) in 1.0 L of developer is required to dissolve the AgBr as Ag ( S 2 O 3 ) 2 3− ( K f = 4.7 × 10 13 )?

0.79 g

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We have seen an introductory definition of an acid: An acid is a compound that reacts with water and increases the amount of hydronium ion present. In the chapter on acids and bases, we saw two more definitions of acids: a compound that donates a proton (a hydrogen ion, H + ) to another compound is called a Brønsted-Lowry acid, and a Lewis acid is any species that can accept a pair of electrons. Explain why the introductory definition is a macroscopic definition, while the Brønsted-Lowry definition and the Lewis definition are microscopic definitions.

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Write the Lewis structures of the reactants and product of each of the following equations, and identify the Lewis acid and the Lewis base in each:

(a) CO 2 + OH HCO 3

(b) B ( OH ) 3 + OH B ( OH ) 4

(c) I + I 2 I 3

(d) AlCl 3 + Cl AlCl 4 (use Al-Cl single bonds)

(e) O 2− + SO 3 SO 4 2−

(a)
This figure shows a chemical reaction modeled with structural formulas. On the left side is a structure with a central C atom. O atoms, each with two unshared electron pairs, are double bonded to the left and right sides of the C atom. Following a plus sign is another structure in brackets which has an O atom with three unshared electron dot pairs single bonded to an H atom on the right. Outside the brackets is superscript negative sign. Following a right pointing arrow is a structure in brackets that has a central C atom to which 3 O atoms are bonded. Above and slightly to the right, one of the O atoms is connected with a double bond. This O atom has two unshared electron pairs. The second O atom is single bonded below and slightly to the right. This O atom has three unshared electron pairs. The third O atom is bonded to the left of the C atom. This O atom has two unshared electron pairs and an H atom single bonded to its left. Outside the brackets to the right is a superscript negative symbol. ;
(b)
This figure shows a chemical reaction modeled with structural formulas. On the left side is a structure that has a central B atom to which 3 O atoms are bonded. The O atoms above and below slightly right of the B atom each have an H atom single bonded to the right. The third O atom is single bonded to the left side of the B atom. This O atom has an H atom single bonded to its left side. All O atoms in this structure have two unshared electron pairs. Following a plus sign is another structure which has an O atom single bonded to an H atom on its right. The O atom has three unshared electron pairs. The structure appears in brackets with a superscript negative sign. Following a right pointing arrow is a structure in brackets has a central B atom to which 4 O atoms are bonded. The O atoms above, below, and right of the B atom each hav an H atom single bonded to the right. The third O atom is single bonded to the left side of the B atom. This O atom has an H atom single bonded to its left side. All O atoms in this structure have two unshared electron pairs. Outside the brackets to the right is a superscript negative symbol. ;
(c)
This figure illustrates a chemical reaction using structural formulas. On the left, two I atoms, each with 3 unshared electron pairs, are joined with a single bond. Following a plus sign is another structure which has an I atom with four pairs of electron dots and a superscript negative sign. Following a right pointing arrow is a structure in brackets that has three I atoms connected in a line with single bonds. The two end I atoms have three unshared electron dot pairs and the I atom at the center has two unshared electron pairs. Outside the brackets is a superscript negative sign. ;
(d)
This figure illustrates a chemical reaction using structural formulas. On the left, an A l atom is positioned at the center of a structure and three Cl atoms are single bonded above, leftt, and below. Each C l atom has three pairs of electron dots. Following a plus sign is another structure which has an F atom is surrounded by four electron dot pairs and a superscript negative symbol. Following a right pointing arrow is a structure in brackets that has a central A l atom to which 4 C l atoms are connected with single bonds above, below, to the left, and to the right. Each C l atom in this structure has three pairs of electron dots. Outside the brackets is a superscript negative symbol. ;
(e)
This figure illustrates a chemical reaction using structural formulas. On the left is a structure which has an S atom at the center. O atoms are single bonded above and below. These O atoms have three electron dot pairs each. To the right of the S atom is a double bonded O atom which has two pairs of electron dots. Following a plus sign is an O atom which is surrounded by four electron dot pairs and has a superscript 2 negative. Following a right pointing arrow is a structure in brackets that has a central S atom to which 4 O atoms are connected with single bonds above, below, to the left, and to the right. Each of the O atoms has three pairs of electron dots. Outside the brackets is a superscript 2 negative.

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Write the Lewis structures of the reactants and product of each of the following equations, and identify the Lewis acid and the Lewis base in each:

(a) CS 2 + SH HCS 3

(b) BF 3 + F BF 4

(c) I + SnI 2 SnI 3

(d) Al ( OH ) 3 + OH Al ( OH ) 4

(e) F + SO 3 SFO 3

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Using Lewis structures, write balanced equations for the following reactions:

(a) HCl ( g ) + PH 3 ( g )

(b) H 3 O + + CH 3

(c) CaO + SO 3

(d) NH 4 + + C 2 H 5 O

(a)
This figure represents a chemical reaction in two rows. The top row shows the reaction using chemical formulas. The second row uses structural formulas to represent the reaction. The first row contains the equation H C l ( g ) plus P H subscript 3 ( g ) right pointing arrow left bracket P H subscript 4 right bracket superscript plus plus left bracket C l with 4 pairs of electron dots right bracket superscript negative sign. The second row begins on the left with H left bracket C l with four unshared electron pairs right bracket plus a structure in brackets with a central P atom with H atoms single bonded at the left, above, and to the right. A single unshared electron pair is on the central P atom. Outside the brackets to the right is a superscript plus sign. Following a right pointing arrow is a structure in brackets with a central P atom with H atoms single bonded at the left, above, below, and to the right. Outside the brackets is a superscript plus sign. This structure is followed by a plus and a C l atom in brackets with four unshared electron pairs and a superscript negative sign. ;
(b) H 3 O + + CH 3 CH 4 + H 2 O
This figure represents a chemical reaction using structural formulas. A structure is shown in brackets on the left which is composed of a central O atom with one unshared electron pair and three single bonded H atoms to the left, right, and above the atom. Outside the brackets to the right is a superscript plus sign. Following a plus sign, is another structure in brackets composed of a central C atom with one unshared electron pair and three single bonded H atoms to the left, right, and above the atom. Outside the brackets to the right is a superscript negative sign. Following a right pointing arrow is a structure with a central C atom with H atoms single bonded above, below, left and right. Following a plus sign is a structure with a central O atom with two unshared electron pairs and two H atoms connected with single bonds. ;
(c) CaO + SO 3 CaSO 4
This figure represents a chemical reaction using structural formulas. On the left, C a superscript 2 plus is just left of bracket O with four unshared electron pairs right bracket superscript 2 negative plus a structure with a central S atom to which two O atoms are single bonded at the left and right, and a single O atom is double bonded above. The two single bonded O atoms each have three unshared electron pairs and the double bonded O atom has two unshared electron pairs. Following a right pointing arrow is C a superscript 2 plus just left of a structure in brackets with a central S atom which has 4 O atoms single bonded at the left, above, below, and to the right. Each of the O atoms has three unshared electron pairs. Outside the brackets to the right is a superscript two negative. ;
(d) NH 4 + + C 2 H 5 O C 2 H 5 OH + NH 3
This figure represents a chemical reaction using structural formulas. A structure is shown in brackets on the left which is composed of a central N atom with four single bonded H atoms to the left, right, above, and below the atom. Outside the brackets to the right is a superscript plus sign. Following a plus sign, is another structure in brackets composed of a C atom with three single bonded H atoms above, below, and to the left. A second C atom is single bonded to the right. This C atom has H atoms single bonded above and below. To the right of the second C atom, an O atom is single bonded. This O atom has three unshared electron pairs. Outside the brackets to the right is a subperscript negative. Following a right pointing arrow is a structure composed of a C atom with three single bonded H atoms above, below, and to the left. A second C atom is single bonded to the right. This C atom has H atoms single bonded above and below. To the right of the second C atom, an O atom is single bonded. This O atom has two unshared electron pairs and an H atom single bonded to its right.

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Calculate [ HgCl 4 2− ] in a solution prepared by adding 0.0200 mol of NaCl to 0.250 L of a 0.100- M HgCl 2 solution.

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In a titration of cyanide ion, 28.72 mL of 0.0100 M AgNO 3 is added before precipitation begins. [The reaction of Ag + with CN goes to completion, producing the Ag ( CN ) 2 complex.] Precipitation of solid AgCN takes place when excess Ag + is added to the solution, above the amount needed to complete the formation of Ag ( CN ) 2 . How many grams of NaCN were in the original sample?

0.0281 g

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What are the concentrations of Ag + , CN , and Ag ( CN ) 2 in a saturated solution of AgCN?

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In dilute aqueous solution HF acts as a weak acid. However, pure liquid HF (boiling point = 19.5 °C) is a strong acid. In liquid HF, HNO 3 acts like a base and accepts protons. The acidity of liquid HF can be increased by adding one of several inorganic fluorides that are Lewis acids and accept F ion (for example, BF 3 or SbF 5 ). Write balanced chemical equations for the reaction of pure HNO 3 with pure HF and of pure HF with BF 3 .

HNO 3 ( l ) + HF ( l ) H 2 NO 3 + + F ; HF ( l ) + BF 3 ( g ) H + + BF 4

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The simplest amino acid is glycine, H 2 NCH 2 CO 2 H. The common feature of amino acids is that they contain the functional groups: an amine group, –NH 2 , and a carboxylic acid group, –CO 2 H. An amino acid can function as either an acid or a base. For glycine, the acid strength of the carboxyl group is about the same as that of acetic acid, CH 3 CO 2 H, and the base strength of the amino group is slightly greater than that of ammonia, NH 3 .

(a) Write the Lewis structures of the ions that form when glycine is dissolved in 1 M HCl and in 1 M KOH.

(b) Write the Lewis structure of glycine when this amino acid is dissolved in water. (Hint: Consider the relative base strengths of the –NH 2 and CO 2 groups.)

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Boric acid, H 3 BO 3 , is not a Brønsted-Lowry acid but a Lewis acid.

(a) Write an equation for its reaction with water.

(b) Predict the shape of the anion thus formed.

(c) What is the hybridization on the boron consistent with the shape you have predicted?

(a) H 3 BO 3 + H 2 O H 4 BO 4 + H + ; (b) The electronic and molecular shapes are the same—both tetrahedral. (c) The tetrahedral structure is consistent with sp 3 hybridization.

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Questions & Answers

what are oxidation numbers
Idowu Reply
pls what is electrolysis
Idowu Reply
Electrolysis is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them. ... Electricity is the flow of electrons or ions. For electrolysis to work, the compound must contain ions.
AZEEZ
thanks
Idowu
what is the basicity of an atom
Eze Reply
basicity is the number of replaceable Hydrogen atoms in a Molecule. in H2SO4, the basicity is 2. in Hcl, the basicity is 1
Inemesit
how to solve oxidation number
Mr Reply
mention some examples of ester
Chinenye Reply
do you mean ether?
Megan
what do converging lines on a mass Spectra represent
Rozzi Reply
would I do to help me know this topic ?
Bulus
oi
Amargo
what the physic?
Bassidi Reply
who is albert heistein?
Bassidi
similarities between elements in the same group and period
legend Reply
what is the ratio of hydrogen to oxulygen in carbohydrates
Nadeen Reply
bunubyyvyhinuvgtvbjnjnygtcrc
Nadeen
yvcrzezalakhhehuzhbshsunakakoaak
Nadeen
what is poh and ph
Amarachi Reply
please what is the chemical configuration of sodium
Sharon
2.8.1
david
1s²2s²2p⁶3s¹
Haile
2, 6, 2, 1
Salman
1s2, 2s2, 2px2, 2py2, 2pz2, 3s1
Justice
1s2,2s2,2py2,2
Maryify
1s2,2s2,2p6,
Francis
1s2,2s2,2px2,2py2,2pz2,3s1
Nnyila
what is criteria purity
Austin Reply
cathode is a negative ion why is it that u said is negative
Michael Reply
cathode is a negative electrode while cation is a positive ion. cation move towards cathode plate.
king
CH3COOH +NaOH ,complete the equation
david Reply
compare and contrast the electrical conductivity of HCl and CH3cooH
Sa Reply
The must be in dissolved in water (aqueous). Electrical conductivity is measured in Siemens (s). HCl (aq) has higher conductivity, as it fully ionises (small portion of CH3COOH (aq) ionises) when dissolved in water. Thus, more free ions to carry charge.
Abdelkarim
HCl being an strong acid will fully ionize in water thus producing more mobile ions for electrical conduction than the carboxylic acid
Valentine
differiante between a weak and a strong acid
david
how can I tell when an acid is weak or Strong
Amarachi
an aqueous solution of copper sulphate was electrolysed between graphite electrodes. state what was observed at the cathode
Bakanya Reply
write the equation for the reaction that took place at the anode
Bakanya
what is enthalpy of combustion
Bakanya
Enthalpy change of combustion: It is the enthalpy change when 1 mole of substance is combusted with excess oxygen under standard conditions. Elements are in their standard states. Conditions: pressure = 1 atm Temperature =25°C
Abdelkarim
Observation at Cathode: Cu metal deposit (pink/red solid).
Abdelkarim
Equation at Anode: (SO4)^2- + 4H^+ + 2e^- __> SO2 + 2H2O
Abdelkarim
Equation : CuSO4 -> Cu^2+ + SO4^2- equation at katode: 2Cu^2+ + 4e -> 2Cu equation at anode: 2H2O -> 4H+ + O2 +4e at the anode which reacts is water because SO4 ^ 2- cannot be electrolyzed in the anode
Niken
Practice Key Terms 8

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Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
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