An example of a strong acid solution is nitdj,hwe2 8bh9i +knv 8h(qx1fhric acid. Which statement is correct for 2qvxi 1hwebn d9h hjhf,k+88 (this solution?

  Which of the following statements concerning aciasp.9)2dpkc+vq ve hh)dz;9kds and bases is not true?

  Which of the following ist , zijdw hx5 (4,)8xnjker. i+6gdifz correct?

  Which statement about a strong acid and itswxnpnmzmg 1221 su rl tv:8m2. conjugate base is correct?

  Which of the following expression wmx ,t-kfng:(s for $K_w$ is correct?

  Which combination of acid and base should be reacted to obtain a basic ce2p.9 d:1ghmdgfw 8u salt?

  A reaction produces carbon dioxide gas and a solution of water with a dissolved mu dgeg7u*/)z salt. W)/g u7e*zgdmu hat could be the reactants?

  Which combination of acid ockom(qb :m83oc*p fsm 51q.f and base will typically have the lowest pH at the equivalence point in a titrmqmb:1*f o8(s pqkco oc3.m5fation?

  In order to prepare a solutioyb q6o8n-pyi 9n of $0.1mol\:dm^{-3}$ with the highest pH, substance XX is dissolved in water. Substance X is

  Water dissociates partially and the value ozjs+:q3 8d -cf)qlxblf the ionic product constant of water atllfd8j )xz+ bq-cq s:3 $25^{\circ}$ 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 converted to ethanosruw**miv xa-v4/v c ;g ub*;aic acid. The \x;uiuva4m-b;*a /v*gvw*sr cce{pH}pH of a bottle of wine changes from 6.5 to 4.5. The concentration of $[H]^+$ is?

  A molecule of HBr reacts with water to 8nbm 7io mwgch8 (d 8;ncn2t4oproduce the charged molecule X. What is the Lewis stnomm42g;7 (i8noh twc d88 ncbructure of molecule X?

  Alkali solutions can be made by dissolving a basic substance in water. mvyz w,+93rj9rei s3 xkb4d 1,pq,qnw
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 nitric12bh9:++mzpw p a 5dwbogr x,q 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 follow v.7p6 kwa0zlp1xx5fcna2g n ,ing statements about acids 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 wi5zyc)/9im)pyn oj(: 4 c n)sqwa3 jchsf*e; indicators 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 repreg+vi/l3i gw 7ey7t5yffjx0qj a(v bd9 3/rbq 3sents $K_a$ for $CH_3COOH$?

  Given the following indicators reb(,mun85 om/9ls el and their behaviours, what will be the correct colours of a solution of 1.0 Mlo se 8b/e 5u9n(mrl,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 smciwg-r l.2 f+l z8q;ic.bj(ltrength 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 hydroge;d( ms wd; rq1x.2onbmn 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 muvkh*w a.hyv1) 2yz3$1.0\,mol\:dm^{-3}$ solutions in order of increasing pH:
$NaOH,Na_2CO_3,NaCl$

  Which of the following reactions is not a neutralization reactioz9raq(j1 .u+i a4gxwp n?

One example of an important buf hscl hdo4p(i /)1ra5mfer 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 reactiou+srtfw (f*+*zrsnfnhtk) e 8x: c+ 1yn between $NH_3$ 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 sl1 zu,amj+5 r$0.001\,mol\,dm^{-3}$ aqueous solution of KOH at 298K given that it ionizes completely?

Consider the following rex+e 1 r vcvqbqaf:j0n1g0+ zr2x5d8ahaction:
$H_2SO_4(aq) + NH_3(aq) \rightleftharpoons HSO_4^-(aq) + NH^+_4(aq)$
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 equal concnv -nd/zfm yr,+bqh-3entrations, form a buffer solutioz v3/q dy rn-nfb,hm-+n?

  $10\,cm^3$ 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 3oe-bzml(mh 7vxtp+3 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 bpeae9h3 . q3ppetween sodium hydroxide aq93h.pe3pae p nd ethanoic acid?

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

  Which statements are correct? :792//mib5xrp6kpz + v e 4+tntq0fm i nlsfsd
I.$CH_3NH_2$ is a Lewis base
II.HOOCCOOH is a Bronsted-Lowry acid
III.$CH^+_3$ is a Lewis acid

  Methanoic acid HCOOHd 0*r5if z 3rlyzp)g1l 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 the equivalen3b6y- 8l2+iety9v iik i syhk5ce point of acid-base titrations is incorrect?lib2evk6h9y 5- ki+3ysi8 yit

  Which of the followingg n ww1lc:jv+9 b*ioku., t-ww salts form basic solutions when dissolved in water?
I.$NH_4Cl$
II.$K_2CO_3$
III.$NaOOCCH_3$

  Which of the following combinv1re5sb ve ;e5ations of $NH_3(aq)$ and HCl(aq) forms a buffer solution?

  The correct sequence it9 v cz+5f -)zt1vcshf8yv fs6n decreasing order of pH for equimolar solutions is:

  Which of the three oxides of period 3 below will cause a change 6y p9b*r; vm-odv-unxin the pH of the solution when theyd-ru-p ;n6boy9 xm*vv react with water?
I.$Na_2O$
II.$SiO_2$
III.$P_4O_{10}$

1. 1.Differentiate between a strong acid and a weak aci txr*ioo(0: lgd.
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 iyrzi8gmw o6 *p+ 7i*p$HNO_3$ molecule are labelled a-d.

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

  Which of the following statementtc-))vd, ej lds about pH is incorrect?

Ethanoic acid reacts with trimethylamine to produce a negativd358aui .t nvjely charged ethanoate ion and another charit3du. vn85ja ged 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-bh 3vwu*5 dfes*ase pairs are correctly matched with the salt formed from their3s5u*hefd *w v reaction?

This question is about the weak acid, car:-n83m)satp 2- ak1 psyfzfq jbonic 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 alx pi3s91i/ kt 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 w,omp *-sn8md dj7vc.nm1g l:x t4 hs(hr*5sopercentage of ethanoic acid. A student wishes to determine the concentration of ethanoic acid in vinegar. She titrates a solution of ethanoic acid ag 4nmo,tmsc(j s l v s*rd1h8pg:-*dhnw5 x.mo7ainst 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 equakmlsnwmgi2n4eix* ;,(/ it .btions is not an acid-base reaction according to the Br/s t2 k;lbinmmginxew(,* . i4onsted-Lowry theory?

Zinc(II) oxide reacts with hydrochloric acid to produce an aqueous solutiosy 77 jfls08 (ild2vosn of zinc and siy(j2s 8vldfs7 07olchloride 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 dilute b2jch)7 7 6+kksmovlk hydrochloric acid in a conical flask, the products are water, positive calcium ob2+ksm k) chjk6l7v7 ions and negative chloride ions.



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

  A bottle contains dilute ethanoic acpmrvr w o)gj94j-ep /(ts:u6n id $CH_3COOH$ 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 pHon*..q+:oteneo od0wwg; 7 tk of a solution of a monoprotic weak acid? o7.+wd ;w*. qgetot0nk: onoe
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 sulphuric acid80csf(dxxoe7fh ly 0(uc;7lx and copper (II) oxidexcs 7 0d8y7;fxl( hfce0oux(l.
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 wez 0vpj)-4 nks irvd4,xof6,0lces. nxak.
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 u pqb)(vqaa kzv+tt3+, )y uo82khpy, Lewis theories are two different theories of classifying aqao3u+)v,y q) +kzu t ( h,vptay8bk2pcids 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, part 1gk -fpj-hug3icularly glass such as 1u- hfgg3k pj-windows. There are many safety warnings on these 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 be expressed usingi rqdk,p:oiz.28ygj . the equation belo8o,..piyrzg2i :jk dqw
$In + H_2O \rightleftharpoons InH^+ + OH^-;K_c = 35
Blue Yellow
Which of the below statements are correct?
I.The solution becomes darker blue with the addition of an acid
II.The solution is a pale green at equilibrium
III.$K_c$ increases with the addition of an alkali

In the amino acid glycine, a hydrogen ion may be trannu0 k3a:q6;:hf c bju8z,ox ausferred from one part of the molecule to another as shown.njbzaoc:a:u 30,qu;khxu6 f8



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-basea+2dwp6dw*rg-xt i0 b pair?