An example of a strong acid solution is nitric aqu5q w 5p bmtk0edm2l4; /z3j7m g,thfcid. Which statement is correct for thislm530,g75dqp fjukh q/;mm z4t2 etb w solution?

  Which of the following statements concerning acids and bases is not in :kn+d. zxgdc(y-n0 true?

  Which of the following is0e3i1xn)n yjx correct?

  Which statement about a strong acid and its conjugate bv8e(w n7 sre;kase is correct?

  Which of the following3v/ kqci.gm6my5vs bb.o-* sh expressions for $K_w$ is correct?

  Which combination of acid and base should be reacted to obtain a basbb;f d4dzf -r)ic salt?

  A reaction produces carbon mf-m 9r8k 17nim9tsl lf;ztk /dioxide gas and a solution of water with a dissolved salt. What could be the reactants sm-kr1n z tftlm9 79/ml8f;ik?

  Which combination of acid and base w8w(hww2no 6 i8:td:+zbl fl3fol6e swill typically have the lowest pH at the equivalence point in a titra: l tn36wwzwffd (slw6ei82b :lo o+8htion?

  In order to prepare a 7:, /va*qxjf0wtjfwu y;ep.t solution of $0.1mol\:dm^{-3}$ with the highest pH, substance XX is dissolved in water. Substance X is

  Water dissociates partially and the valu3q4 djk5ly4m r)hzp 6qe of the ionic product constant of water at mh)34jzp ldk6qrq 45y$25^{\circ}$ is $1.00\times10^{-14}$.
1.State an equation for the dissociation of water.
2.Calculate the pH of a $0.0100mol\:dm^{-3}$ of lithium hydroxide at 298K.  
3.Explain whether a $0.0100mol\:dm^{-3}$ solution of calcium hydroxide will have a higher or lower pH than a $0.0100mol\:dm^{-3}$ solution of lithium hydroxide at the same temperature.  $mol\:dm^{-3}$

  When wine is exposed to air, k0,scgzig*rmq a 6 3/ chxz4,ithe ethanol is slowly converted to ethanoic acid. The \ce{pH}pH of a bottle of wine changes from 60q,amk gic /c*4rzhig szx3,6.5 to 4.5. The concentration of $[H]^+$ is?

  A molecule of HBr reacts with water to produce the charged molecule X. Whax;av+,g 6zpsvea0 6ks t is the Lewis structure oa0s;6za+g 6 v,s pvkexf molecule X?

  Alkali solutions can be made by dissolving a b si1(c+ gqwy6n. ,eezbasic substance in water.
1.Determine the concentration of a solution of NaOH made by carefully dissolving 5.00 g of NaOH in sufficient distilled water to make $250.0cm^3$ total solution in a volumetric flask.  $mol\:dm^{-3}$
2.An indicator was added to the solution made in (a), and it turned red. Using section 22 (Section 18- 2025 syllabus) in the Data booklet, state a possible indicator used.
3.The temperature of a $50.0cm^3$ sample of the solution containing the indicator from (b) was found to be $22.0^{\circ}C$. Suggest with a reason, two possible observations if a slightly larger quantity of HCl was added and stirred.
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers for the 2025 syllabus.

  An aqueous solution of nitymiq -sok*/e,lc j33)pmc; lwric acid $HNO_3$ has a pH of 4. How many moles of this acid are found in $1 dm^3$ of the solution?

  Which one of the following statements about acidas-o t6hgpp6pv tg) 50s is/are true?
|. Acids will neutralize bases to form salts
||. Acids produce solutions with pH greater than 7
|||.Acids ionize to form $H^+$ ions when dissolved in water

  What statements about i(.(;v- elau wncrhn7 kndicators are correct?
|.Indicators are typically weak acids or weak bases
||.Indicators are different colours in acidic and alkaline conditions
|||.The midpoint of the colour change of an indicator occurs when [$HIn$] = [$In^-$]

  A solution of $1.0\:mol\:dm^{-3}$ HCl is diluted to $0.1\:mol\:dm^{-3}$. Which statement is correct?

  Which expression representsjiuv p05lo7plb2 *u; b $K_a$ for $CH_3COOH$?

  Given the following indicators and their behaviours,/no;x v9p) gld what will be the correct colours / o9g)v p;dlxnof a solution of 1.0 M KOH tested with each indicator?

Indicator	pH range	Colour change (Acid- alkali)
Methyl orange	3.1- 4.4	Red – Orange
Bromocresol green	3.8 - 5.4	Yellow - Blue
Phenolphthalein	8.3 - 10.0	Colourless - Pink

  What is the order of increasing acid s/:, z0,4rmcjjlqtji ctrength based on the $pK_a$ values below?

Acid	$pK_a$
$CCI_3COOH$	0.66
$HCOOH$	3.75
$C_6H_5OH$	9.99
$CH_3OH$	15.5

  The structure of thepwpaw+m:-p3a*+sln d hydrogen phosphate ion is shown.


How many $H^+$ ions can react with one hydrogen phosphate ion?^+ions can react with one hydrogen phosphate ion?

  Place the following *n9*ehdn +uo e pz1lo5$1.0\,mol\:dm^{-3}$ solutions in order of increasing pH:
$NaOH,Na_2CO_3,NaCl$

  Which of the following reactions is not a neutralizatiosl ka+)h 0si52oq5fbmn reaction?

One example of an important buff ,w jq*nr8nt-h8t2wg )shw6vqer system is the $H_2CO_3/HCO_3^-$ buffer in our blood.
1. 1.Define buffer solution.
2.Using relevant equations, describe how the $H_2CO_3/HCO_3^-$ buffer works.
A student has solutions of $0.5\,mol\,dm^{-3}$ $NaOH,HCl,H_2CO_3andNaHCO_3$.
2.State two ways the $H_2CO_3/HCO_3^-$buffer can be made from these solutions.

  The reversible reaction between 2u)hbf 4pge:d.:gb4 en 7dzhx$NH_3$ and $H_2SO_4$ is:
$NH_3 + H_2SO_4 \rightleftharpoons NH^+_4 + HSO_4^-$
Which compounds act as bases in the forward and backward reactions?

  What is the pH of a 5:z9wo,e g/7dl0k5.htgwpdjohss) e$0.001\,mol\,dm^{-3}$ aqueous solution of KOH at 298K given that it ionizes completely?

Consider the following reaciy . qp(jei-8dx 44;xek0l0jof z; pzrtion:
$H_2SO_4(aq) + NH_3(aq) \rightleftharpoons HSO_4^-(aq) + NH^+_4(aq)$
1. 1.Define a Brønsted-Lowry acid and a Lewis acid.
2.Deduce the two species acting as acids and their conjugate bases in the equation above.
2.Give an example of a species that is a Lewis acid but not a Brønsted-Lowry acid and explain why this is the case.

  Which of the following solutions, when mixed with equal volumes at efde,kx2mu1 uijq.2l 5qual concent,2qjefi1l kd5. um2 xurations, form a buffer solution?

  $10\,cm^3$ of an aqueous solution of HCl with pH 1.0 is mixed with $990\,cm^3$ of water. The pH of the formed solution is:

  $20\,cm^3$ of $0.100\,mol\,dm^{-3}$ NaOH were slowly added to a $10\,cm^3$ sample of $0.100\,mol\,dm^{-3}$ HCl,and the pH was measured throughout the addition.
The equation for the reaction is as follows: $NaOH(aq) + NCl(aq) \rightarrow NaCl(aq) + H_2O(l)$
The ionic product constant of water at $25^{\circ}C$ is $1.00\times10^{-14}$
1.Calculate the number of moles of NaOH remaining at the end of the addition.Mole ratio is 1:1 and NaOH is in excess by  $\times10^{-3}\,mol$
2.Calculate the concentration of $OH^-$ at the end of the addition.  $mol\,dm^{-3}$
3.Using your value for $[OH^-]$ in (b), calculate the pH of the solution at the end of the addition.  

  Concentrated sulfuric acid behaves ae1u7l5r,(m + ymhj hhws a strong acid when it reacts with water:
$H_2SO_4(aq) \rightarrow H^+(aq) + HSO^-_4(aq)$
$HSO_4^- \rightleftharpoons H^+(aq) + SO_4^{2-}(aq)$
Which of the following is (are) true for $1.0\,mol\,dm^{-3}$ of sulfuric acid?
I.$[H^+]$ is high
II.$[SO_4^{2-}]$ is high
III.$[SO_4^{2-}] = [HSO^-_4]$

  Which indicator would be most suitable for a titration between so c0 0;q8rjh8xbmgkgz/dium hydroxide and ethanoic acj8k08cmqz g0;r gbh x/id?

Indicator	pKa
Methyl orange	3.7
Bromocresol green	4.7
Bromothymol blue	7.0
Phenolphthalein	9.6

  Which statements are c*bq zkw;:3ce correct?
I.$CH_3NH_2$ is a Lewis base
II.HOOCCOOH is a Bronsted-Lowry acid
III.$CH^+_3$ is a Lewis acid

  Methanoic acid HCOOH p zted4- :qm4mckv81mm)d 3az is a weak acid.
1.State the formula of the conjugate base of HCOOH.
2.HCl is a strong acid and dissociates in water as shown below:
$HCl(aq) \rightarrow H^+(aq) + Cl^-(aq)$
1.Suggest the pH of the solution formed when HCl dissolves in water.
2.Compare the relative strengths of the respective conjugate bases of HCOOH and HCl.\ce{pH}pH value less than  
3.$0.01\,mol\,dm^{-3}$ of a given monoprotic acid HA has a pH of 3.
1. This acid is  ----待选择----weakstrong .
2.Compare the electrical conductivity of HA(aq) and $HNO_3(aq)$, giving a reason for your choice.

  Which statement about thenh m3 x1p5b1mt1dnwjabu3or* 3m /lx) equivalence point of acid-base titrations is incorrectw 3 1/*bxm3d5atn1bnh1) jx oulrmpm3 ?

  Which of the following salts form basic solutions when diss. e-lvt1bi u9wolved in water?
I.$NH_4Cl$
II.$K_2CO_3$
III.$NaOOCCH_3$

  Which of the following combx3l uc y40:ixbinations of $NH_3(aq)$ and HCl(aq) forms a buffer solution?

  The correct sequence in decreasinpe vn;wjs3n16 k+qzs5aide42 g order of pH for equimolar solutions is:

  Which of the three oxide :b2g ro3atw0xs of period 3 below will cause a change in the pH of the solution when they react with waterw0ro2g3tb: xa?
I.$Na_2O$
II.$SiO_2$
III.$P_4O_{10}$

1. 1.Differentiate between a stro3,lwo:sd)fyh *e jsk(c :4esgkk f7z.ng acid and a weak acid.
2.State a balanced equation for the reaction between KOH and $HNO_3$.
Measuring the pH can be useful when trying to differentiate between different solutions.
A student has three unlabelled bottles of white powders. They know that the bottles contain either $KOH,KOOCCH_3 or HNO_3$.The student has access to a pH meter and distilled water.
2.Outline how the student can determine which powder is inside each of the three unlabelled bottles. Include equations where relevant.

  Four features of the jrqvcw *b8w el1am2 (;$HNO_3$ molecule are labelled a-d.

Why is one mole of $HNO_3$ able to react with one mole of NaOH?

  Which of the following statements/o5 6 2w+vqq/s mzd w ppqs;6dij8yj;g about pH is incorrect?

Ethanoic acid reacts with trimethylamine t;9 a fsgvuk9ofwc39n:o produce a negatively charged ethanoate ion and another charged compound; vu9f3g a n9s:w9fkoc X.


1.Ethanoic acid and the ethanoate ion differ by one hydrogen ion. State the name given to a pair of molecules that differ in this way.
2.State why trimethylamine is categorised as a Brønsted-Lowry base.
3.Ethanoic acid can be represented as $CH_3COOH$. This formula provides a better description of the bonding in the molecule than the alternative formula $CH_3CO_2H$.
1.Suggest why it is better to represent the structure of ethanoic acid as $CH_3COOH$ than as $CH_3CO_2H$.
2.The formula of compound X is $(CH_3)_3NH^+$.Draw the structural formula of compound X.
4.Water can react with both ethanoic acid and trimethylamine.
1.The reaction of water with ethanoic acid produces an ethanoate ion and another charged compound Y. State the formula of compound Y.
2.State the property of water and trimethylamine that allows them both to react with Brønsted-Lowry acids.

  Which of the following acid-base pairs are correctly matched with the salt for/,x1l-wb6x bfwl 7m seri/+vf med fb6xfmws/f/,l7 r+wx 1be-l virom their reaction?

This question is about the weak acid, carbonic aj-y)vugro .0vg ef5l8 cid $H_2CO_3(pK_{a1} = 6.35)$.
1. 1.Determine the pH of a $0.175\,mol\,dm^{-3}$ solution of carbonic acid.
2.State one assumption made in your answer to (a)(i).
Carbonic acid is a diprotic acid so can undergo two dissociations. The second dissociation has a $pK_{a2}$ of 10.33.
2. 1.State the equation for the second dissociation of carbonic acid.
2.Comment on the degree of dissociation for this second proton, based on the value of $pK_{a2}$.

  Indicators are used to determine the endpoint o 4rvnm 1i(zad+f a titration.
1.Using a relevant equation, explain how acid-base indicators work.
2. 1.Calculate the pH of a $1.0\,mol\,dm^{-3}$ solution of KOH.pH=  
2.Calculate the pH of a $0.5\,mol\,dm^{-3}$ solution of $HNO_3$.pH=  
3.Using section 22 (Section 18- 2025 Syllabus) of the data booklet, suggest a suitable acid-base indicator for a titration between the solutions in (b)(i) and (b)(ii).
4.On the following axis, sketch the titration curve for the titration between the solutions in (b)(i) and (b)(ii), starting with $10\,cm^3$ of $HNO_3$ solution in the flask, and titrating with KOH.

  Commercial vinegar contains a small percentage of etm/z40wv7j;r 8 qwxg 17 zn-kejkl2w tthanoic acid. A student wishes to determine the concentration of ethanoic acid in vinegar. Sh7z;0wkw8t jr1zj 2wn7gkl/x4v et -mqe titrates a solution of ethanoic acid against a standard solution of potassium hydroxide of concentration $8.0\times 10^{-4}\,mol\,dm^{-3}$. The equation for the reaction is:
$CH_3COOH(aq) + KOH(aq) \rightarrow CH_3COOK(aq) + H_2O(I)$
A volume of $25.0\,cm^3$ of vinegar was diluted with distilled water and made up to a volume of $250.0\,cm^3$ in a volumetric flask. A burette was filled with the diluted solution.
$25.0cm^3$ of potassium hydroxide solution was added to a conical flask and three drops of phenolphthalein indicator added.
1.Ethanoic acid is considered a weak acid. Define the term ‘weak acid’.
2.The results of the titration are shown in the table below:

Trial	Volume of Titre$(cm^3)$
1	21.0
2	21.2
3	20.8

1.Using section 22 (Section 18- 2025 Syllabus) of the IB data booklet, identify the color at the endpoint.
2.Calculate the concentration of dilute ethanoic acid.  
3.Calculate the concentration of ethanoic acid in vinegar.  $\times10^{-4}\,mol\,dm^{-3}$
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers in the 2025 syllabus.

  Which of the following equations is not an acid-base reaction accordi x/3uxosgq5d xn; y cb/,0ak(ing to the Bronsted-Lowry thesoy;(ci5kg,q/un xx ab/ d0x3 ory?

Zinc(II) oxide reacts with hydrochloric acid to produce an aqueous solution m l*t x+bt43 nkr,3 urg7kx0meof zinc and chloride ions.kget4r* l tmx r3u3kb0m7,xn+
$ZnO(s) + 2HCl(aq) \rightarrow Zn^{2+}(aq) + 2Cl^-(aq) + H_2O(I)$
1.HCl is described as an acid because it is a hydrogen ion donor. State the term used to describe acidity of this type
2.State the conjugate base of HCl in this reaction, giving a reason for your answer.
3.An aqueous solution of HCl does not contain molecules of HCl. Draw the structural formula of the positively charged molecule formed in the solution, including the positive charge.
4.Zinc(II) oxide is amphoteric.
1.Define the term amphoteric.
2.Suggest a reaction that could be performed to confirm that zinc oxide is amphoteric, giving your reasoning.
3.Explain why zinc(II) oxide is not amphiprotic.

$H_2O$ is an example of an amphiprotic species meaning it can act as either an acid or base.
1. 1.Draw the Lewis structure of $H_2O$.
2.Explain why $H_2O$ can act as both a Brønsted-Lowry acid and Brønsted-Lowry base.
3.Explain why $H_2O$ can act as a Lewis base.
2. 1.State an example of an acid-base reaction where $H_2O$ acts as a Brønsted-Lowry acid and another where $H_2O$ acts as a Brønsted-Lowry base.
2.State an example of a Lewis acid-base reaction that is not a Brønsted-Lowry acid-base reaction where $H_2O$ acts as a Lewis base.

  When powdered calcium oxide is added to dilute hydrochloric acid in a co)yw ( hp*wfj*d(lf wr/nical flask, the p yh*w/f wjf )l*wrdp((roducts are water, positive calcium ions and negative chloride ions.



Which species is the conjugate base of hydrochloric acid in this reaction?

  A bottle contains dilute ethan dob5bp5) tz6yoic acid $CH_3COOH$ of unknown concentration. To determine the concentration of the acid, a student titrates the acid against a standard solution of KOH according to the following equation:
$CH_3COOH(aq) +KOH(aq) \rightarrow CH_3COOK(aq) + H_2O(I)$
1.Calculate the mass of KOH that must be used to prepare $400.0\,cm^3$ of a $0.100\,mol\,dm^{-3}\,KOH$ solution.n=  mol , m=  g
2.Calculate the pH of the $0.100\,mol\,dm^{-3}\,KOH$ solution given that it ionizes completely in solution as shown in the following equation: $KOH(aq) \rightarrow K^+(aq) + OH^-(aq)$ pH=  
3.During the titration, the student finds that exactly $20.0\,cm^3$ of the KOH solution neutralizes exactly $25.0\,cm^3$ of the $CH_3COOH$ solution. Calculate the concentration of the $CH_3COOH$ solution.C=  $mol\,dm^{-3}$

  Hydrogen sulfide,$H_2S$, is a weak acid with a $pK_a$ of 7.04.
1.1.State the acid dissociation constant expression for $H_2S$.
2.Calculate $K_a$ for $H_2S$.  $\times 10^{-8}$
2.1.State the base dissociation constant expression for $HS^-$.
2.Calculate $K_b$ for $HS^-$ assuming a temperature of 298K.  $\times 10^{-7}$
3.Using your answers to parts (a)(i) and (b)(i), derive the equation $K_w =K_a \times K_b$

  Which quantities are required to calculate the pH of a solu ;uyj03.nstx )7xha) :phxikxtion of a monoprotic weak acid? h3x)yjx)s k0uh;x:np a.x7i t
I.The $pK_a$ of the weak acid
II.The concentration of the solution
III.The value of $K_w$

1.State the complete balanced equation for the reaction between z-ld w4dg9eaail38q* sulphuric acid and copper (II)lgqlw -*e8 azai3dd94 oxide.
2.State the complete balanced equation for the reaction between ethanoic acid and potassium carbonate.
3.Outline two ways to monitor the rate of reaction for reaction (b) above.

  Acids and bases can be classified as strong owhiea4ms2-. or weak.
1.Explain why ammonia,$NH_3$ in an aqueous solution, acts as a weak base, using an equation.
2.An experiment was carried out to determine the energy change during the following reaction:
$2NH_3(aq) + H_2SO_4(aq) \rightarrow (NH_4)_2SO_4(aq)$
Initial temperature of each solution =$21.4^{\circ}C$
Final temperature of the mixture = $23.8^{\circ}C$
1.State with a reason whether the sign of the enthalpy change for this reaction is positive or negative.
2.Suggest with a reason whether the magnitude of the enthalpy change will be  ----待选择----greatersmaller  if aqueous ammonia is replaced with potassium hydroxide.
​

The Brønsted-Lowry and the Lewis theories are two different theories oejmp,t.aj98yp rmr2 i;e tw;+f classifying acids and jpt mm8p r.92wr,+;; eijteya bases.
1. 1.Distinguish between the Brønsted-Lowry theory and the Lewis theory.
2.Define incomplete octet.
Consider the dimerization of $AlCl_3$:
$2AlCl \rightarrow 3Al_2Cl_6$
2. 1.Draw structural formulas to represent this reaction.
2.Explain how this is an acid-base reaction under the Lewis theory but not the Brønsted-Lowry theory.

  The pH of a $0.1\,mol\,dm^{-3}$ solution of phenol is 5.0. What is the approximate $K_a$ of phenol?

  A student reacts a $15\,cm^3$ sample of $0.10\,mol\,dm^{-3}$ methylamine,$CH_3NH_2(K_b = 4.47\times 10^{-4})$,with $10\,cm^3$ of $0.10\,mol\,dm^{-3}\,HNO_3$.
1. 1.Calculate the initial number of moles of methylamine in the sample.$n(CH_3NH_2)_{initial}$ =   $\times 10^{-3}$
2.Calculate the final number of moles of methylamine after the neutralization reaction.
2.Calculate the pOH of the final solution.pOH=  

Aqueous ammonia solutions 2 ;e s/:ezromi ryea.7(ouba0are commonly used to clean in houses, particularly glass such as windows. There are many safety warnings on thoz/ya be7a: urr ;0(so2eiem .ese products.
1.Ammonia mixed in water forms ammonium hydroxide. State the equation for this process.
2.One concern is that ammonia solutions could mix with acidic cleaning products, such as drain cleaner with sulphuric acid.
1.Determine the balanced equation for ammonium hydroxide reacting with sulphuric acid.
2.Suggest a reason this reaction could be dangerous.

  The function of the acid-base indicator, In, can *12cnig er:2lj )pxstbe expressed using the equation below*s1gixr2):c t 2ln jpe
$In + H_2O \rightleftharpoons InH^+ + OH^-;K_c = 35
Blue Yellow
Which of the below statements are correct?
I.The solution becomes darker blue with the addition of an acid
II.The solution is a pale green at equilibrium
III.$K_c$ increases with the addition of an alkali

In the amino acid glycine,lgeuq;1cib4 zc2zx 7- a hydrogen ion may be transferred from one part of the mobzgecziu27 -xlc ;q 14lecule to another as shown.



In this reaction, glycine acts as both a Brønsted-Lowry acid and a Brønsted-Lowry base.
1.State the part of the glycine molecule that acts as a Brønsted-Lowry acid in the forward reaction, giving a reason for your answer.
2.In an aqueous solution of glycine, the transfer of the hydrogen ion may involve two reaction steps. The first reaction step is shown.


(i)By considering how a hydrogen ion forms from a hydrogen atom, explain why the hydrogen ion is often referred to as a proton.
(ii)Explain why $H^+$ is not an accurate representation of the cation formed in this reaction.
3.Amino acids such as glycine can be used to produce long molecules called peptides. The shape of the peptide molecule is determined by the types of intermolecular interactions present between the amino acid side chains, which have different structures. Part of a peptide molecule is shown, with the side chains highlighted in bold.


Suggest why acid-base reactions could alter the shape of this peptide chain.

  Which of the following is a conjugate acid-base h aw9(q0(awl ukq5y,w pair?