An example of a strong acid solution is nitric aciq wsmh+4m )x9ed. Which statement is correct for this solutim9q 4hesm+) wxon?

  Which of the following statements concerning acids and base 06nb gpou7d gyo;cj0)s is not true?

  Which of the following nj*cg4a-y 1oflwu(6 v is correct?

  Which statement about a strong acid and its conjugate base is cor3jgfv* p(8 uulrect?

  Which of the following expressions f5x8 31tlmvmq,9n vliy jzx5h .or $K_w$ is correct?

  Which combination of acid and base should be reacted to obtain a v)(y rn0bl2(6vat q gqbasic salt?

  A reaction produces carbon dioxide gas and a solution of water with a dissolve )se;8sb3os lfd salt. Whaos e;fs 38bl)st could be the reactants?

  Which combination of acid and base will typically have the lowest pH at t q+6f3l q;igothe equivalence poi3i q 6;lf+qgtont in a titration?

  In order to prepare a sojmnp*2a g hs6j cep0.4lution of $0.1mol\:dm^{-3}$ with the highest pH, substance XX is dissolved in water. Substance X is

  Water dissociates partially and the value oxjb77 p ,cgm-atmka3 :f the ionic product constant of water3 txmkb aacmp7g:7-,j at $25^{\circ}$ 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, the ethanol is slowly convertedx6tu11ps7v ,uc8s. i g*l/oxwkcld9o to ethanoic acid. The \ce{pH}pH of a bottle of wine changes from 6.5 to 4.5. The concentodl *uk1.1ut6ocgls xx7s8 wi ,c/v9pration of $[H]^+$ is?

  A molecule of HBr reacts with water to produce the charged molecule X/es -:flx yfd9. What is the e f9dx y/slf-:Lewis structure of molecule X?

  Alkali solutions can be made by dissolving a basirq,1,juwyfk 4n.km :t:fa xi2 c 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 nitric acid ;c cb (1jbog,3dz+d hc$HNO_3$ 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 acids is/are trudn ,h/zho2q f(1,oswnfr lp+3e?
|. 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 i7f,iwvdku-l g) 4dq w+ndicators 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 rep(gqo5 a loz0b59yqy9 xt 4)ppqresents $K_a$ for $CH_3COOH$?

  Given the following indicators and their behaviours, what will be thixf a)r3rk.lpz;iwo7 s(/u2 v(1 tlqee correct colours of a solut ll;7.ii) wa 2pket ( zfqrv/urs3xo1(ion 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 st 5 spwv*2 owx8k1ily)qrength 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 the hydrogen phosphate ion m r 6 so9*is7k.zp9tjtis shown.


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

  Place the following bp4db ,kbw)oh9ov5,n$1.0\,mol\:dm^{-3}$ solutions in order of increasing pH:
$NaOH,Na_2CO_3,NaCl$

  Which of the following + 2axm(f1lndo;3k f((fwwk g oreactions is not a neutralization reaction?

One example of an important buffer system av59 r*wzpii4is 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 bn-io8cjj,p1+ vdr*za etween $NH_3$ 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 neiu5pfr:1 f;f (sbt9 $0.001\,mol\,dm^{-3}$ aqueous solution of KOH at 298K given that it ionizes completely?

Consider the following5*thivww h+biq1 l.1ay i(x1 p reaction:
$H_2SO_4(aq) + NH_3(aq) \rightleftharpoons HSO_4^-(aq) + NH^+_4(aq)$
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 solutionsit*o7zr gi0k* psp2r), when mixed with equal volumes at equal concentrations, form a buffe*p 72)*potkgzis irr0r 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 as a strong acid when it reacts wprbdlx+ /5al:)i n zx x;r*/fiith 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 sodium hydro5 fnbw 7ym4)gaxide anfyb75)n4 amwgd ethanoic acid?

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

  Which statements are corre ica*t, g,bg1*nx )deyct?
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 is a weak aci. zsh)un57kh.pkyk j5 d.
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 the equivalence point of acid-bas,x7to3 n-b0i)lcl w ynsct.7 ve titrations is incorrectb,yw7 t3-xv l0.)locc7nitns ?

  Which of the following salts f)4enlj 1gfw q*sk r7s*orm basic solutions when dissolved in water?
I.$NH_4Cl$
II.$K_2CO_3$
III.$NaOOCCH_3$

  Which of the following combinam67ekpbvsv 8j2tn8h( tions of $NH_3(aq)$ and HCl(aq) forms a buffer solution?

  The correct sequence in decreasing order of pH for eque ok d7o2e -*xqpl)my+imolar solutions is:

  Which of the three oxides of period 3 below will cause a change in the pHy8d8 lq7 gzp-y. htgy1xo/1lw of the solution when they re1h 8ly8xq .d gwgtzp- /yyo17lact with water?
I.$Na_2O$
II.$SiO_2$
III.$P_4O_{10}$

1. 1.Differentiate between a s q5n762kzbbsq2fnugc0.r)crg c ai+ , trong 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 y; 1g; yjjwtwkse0;-u$HNO_3$ molecule are labelled a-d.

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

  Which of the following sta3im34 2csjwdn tements about pH is incorrect?

Ethanoic acid reacts with trimethyla vv:rb +xzp4*rmine to produce a negatively charged ethanoate ion and another chaxr* :v+rzb4pvrged compound 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 ;4prtm 8i v*zj-e7ob fare correctly matched with the salt formed from their reactm8 -zt ifb;*7 ev4projion?

This question is about the weak acidobwby* (p2 9f r):mwyv, carbonic acid $H_2CO_3(pK_{a1} = 6.35)$.
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 of a titrdd (,fxjfg h5 b 4(o)-ppga8elation.
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 ethanoic acid. A student wishex5ah1m1-p- ( xmagkuzs to determine the concentration of ethanoic acid in vinegar. She titrates a solution of ethanoic acid against a standard solution of potassium hydroxide of concentratxmm 5gh-pxa1 kazu-(1ion $8.0\times 10^{-4}\,mol\,dm^{-3}$. 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 accordin,8rpfmn q -(ong to the Bronsted-Lo,no fpmq8 rn-(wry theory?

Zinc(II) oxide reacts with hydrochlory6e p x:b7kbte7u 92:srhm-u sic acid to produce an aqueous solution of zirm:u7bh69 s -e2yb7xkepu:t snc and chloride ions.
$ZnO(s) + 2HCl(aq) \rightarrow Zn^{2+}(aq) + 2Cl^-(aq) + H_2O(I)$
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 dilu roupbe 7arlh0w-3y38te hydrochloric acid in a conical flask, the ub73 p03r-hyl r8eaow products 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 ethanoic ac*0ve/qm yvw :mid $CH_3COOH$ 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 y4.m 5rda w yybh/a2)acalculate the pH of a solution of a monoprotic weak a2yhbamryyw. ad4 a5/ )cid?
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.eo:qakd98wx lo t79i / 3iapz sulphuric acid and copper (II) oxid a wpo/lqex97 k3di:t ai9z.o8e.
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 or v.c 3tgwl:/+wvwv-yr 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 f*54o )gr,1ntvfj1boz9o 2(s yirx ci theories are two different theories of classifyjr fy) n rfxv2*b,5o4o1(t i9iszocg1 ing acids and 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 are commonly used to clean in houses, partielit3ykeczja ygi3x7 49 4r*2cularly glass such as windows. There are many safety warnings on these products. a247*r 3y z94ic l3ekigxtjye
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 indicator3syj1.hv*x gi4li, i - udk(gy, In, can be expressed using the equation bs3hgjkil,g uy.iy(d*-v ix14elow
$In + H_2O \rightleftharpoons InH^+ + OH^-;K_c = 35
Blue Yellow
Which of the below statements are correct?
I.The solution becomes darker blue with the addition of an acid
II.The solution is a pale green at equilibrium
III.$K_c$ increases with the addition of an alkali

In the amino acid glycine, a hydrogen ion may be transferrewge e3wg8+o;cd from one part of the molecule to another as shoeo3gw e;+g8c wwn.



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 conjugal t/w/;ll d:2pue qzt 1:(wbnt8 a*sjdte acid-base pair?