An example of a strong acid solution /f2aj* kl*ggeis nitric acid. Which statement is correct fo/ *gajfg2* kelr this solution?

  Which of the following statements concerning acids and bases is notv5 3 u afejonw0(.c6br true?

  Which of the following is corrkvuk 9bo m*wi -xtv:t+g.8uk6kkj z-(ect?

  Which statement about a zmah:3 1 /npl+mcm7xk strong acid and its conjugate base is correct?

  Which of the following expres70 b oduu*nt4 ezobv91sions for $K_w$ is correct?

  Which combination of acid and base should be reacted to obtain a bashs 7, (z. exqp6koqka2ic salt?

  A reaction produces carbon dioxide gas and a solution of water wi 36tl/ lvc17nc;t ia t()gygiu)p /slith a dissolved salt. What could be thelt )i3t( clp 1ns g /iytv/u;6glac7i) reactants?

  Which combination of acid and base will typically have the l cyn;)avke a/)kdl( ldmac5(1owest pH at the equivalence poin/dycvd)(ae5k l) n1 cam(k l;at in a titration?

  In order to prepare a solution ofkzg1sjr 0j7 i .zzn1-l $0.1mol\:dm^{-3}$ with the highest pH, substance XX is dissolved in water. Substance X is

  Water dissociates partia*x5jy 9o,rd)u+4ffsh8opizz lly and the value of the ionic product constant of water at 5izpf s + 9zfr odj,yh84ox*u)$25^{\circ}$ 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, thj*6lv7xzohwv9x gbd)wtao*4 rk e8w5.r3o0x e ethanol is slowly converted to ethanoic acid. The \ce{pH}pH of xl v 6oge35 7bz* wajdv4wrko89xtr.0*oxwh)a bottle of wine changes from 6.5 to 4.5. The concentration of $[H]^+$ is?

  A molecule of HBr reacts with water to pr4-w-lw,uu ni+no8l wx.qb )h 3ful4inoduce the charged molecule X. What is the Lewis structure of moleculownw n ilqblnhwlu,48)u.-ifx34 + u-e X?

  Alkali solutions can be0k 21 p7u2nvg(i1jeky mr-rhf og1w,c made by dissolving a basic 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 nbl )z c+c (w9bj*jvnvg4*rktg4m ).oacid $HNO_3$ 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 thc . dpu8tw+u8:(mkkj1lw v+y- ow5gmrue?
|. 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 indi4vn csgl p),n-vuq36 rcators 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 represepwondc (v32q 4nts $K_a$ for $CH_3COOH$?

  Given the following indicators and their bkg0pogo/d, n ;ehaviours, what will be the correct colours of pg o0d,; kgon/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 ;m-yohuhxo; 5*wx(kl increasing acid strength 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 phoi zeltzn yh .7y7l)v+)sphate 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 bp8a4 l0-lhaz qts8 2z$1.0\,mol\:dm^{-3}$ solutions in order of increasing pH:
$NaOH,Na_2CO_3,NaCl$

  Which of the following reactions is notk2cawwu/ *1i) i jonkty( 6oi6 a neutralization reaction?

One example of an importt u k0n17xhya k8ea.4sant buffer 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 betweqkozzyg:v6i)zjt- r4 ss om.4)5.harfi)4dsen $NH_3$ 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 wd2w)6i./d vxl4 +mysw0zcz h $0.001\,mol\,dm^{-3}$ aqueous solution of KOH at 298K given that it ionizes completely?

Consider the following re46owxdza q.0 tcqh/h (action:
$H_2SO_4(aq) + NH_3(aq) \rightleftharpoons HSO_4^-(aq) + NH^+_4(aq)$
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 9vp4 15h uliipsolutions, when mixed with equal volumes at equal concentii4v5 1lh9up prations, 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 as a strong qa,dv h4d5 +xfacid 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 sodium hydrol3hjsm+h 3 29rev giy(xide and ethanoic acid39 meshhigjv y+3(r2l?

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

  Which statements are correct8i rz2oc;x7qo?
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 acid.+cjh9m*(f: gw, nou wn
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-base titratin8 c poyjac0(-ons is incorrect-0pca yjoc (n8?

  Which of the following salts form basic solutions when di4wtl di*tl0kt1ct .v, exbk)3ssolved in water?
I.$NH_4Cl$
II.$K_2CO_3$
III.$NaOOCCH_3$

  Which of the following crv uij05, t2++w olughombinations of $NH_3(aq)$ and HCl(aq) forms a buffer solution?

  The correct sequence in decreasing order of pH for equimolar solutions is lr2dfum+/ qvqm9: d r8xgl2*s:

  Which of the three oxides of period 3 below will cause a clq.58dd*r ae,nltct - /u gjt5hange in the pH of the solution when they react d etd-8 ,lqu .tj/rgla5*5tnc with water?
I.$Na_2O$
II.$SiO_2$
III.$P_4O_{10}$

1. 1.Differentiate between a strong acid and a weah w-r nd6rd 88j.8agx y2wvy2ok 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 thejc rct6 5ua3mpyo(mptw18 2(v $HNO_3$ 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 about pH is inco4bir ;6an /gbfl8-we hrrect?

Ethanoic acid reacts with trimethylamine to p.cfa k(fos;s- roduce a negatively charged ethanoate ion and another charged compound X.fsacf(ok - ;.s


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-babb:z4rlzd al 9yu7 3c;se pairs are correctly matched with the salt formed from thei:4bzu3l c;da79lyzbr r reaction?

This question is abo3b59 worsq wa.ut the weak acid, 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 determi q6b3 qs.fo-lbne the endpoint of 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 perceqzhfwpt i 8a3)l(zi3 ix;*rqp 70xlt+ntage of ethanoic acid. A student wishes to determine the concentration of ethanoic acid in vinegar. She titrates a solution of ethanoic acid against a standard x07r i ttzi8p; a hfw)qi3(lzlpx*+q3solution 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 equatiotphi0izjw1* w/qvpg(5qa p0ibce2: n9 u* el4ns is not an acid-base reaction according to the Br it:iqeubc*qwwe *h2p0plpv (ajz195i ng04/ onsted-Lowry theory?

Zinc(II) oxide reacts with5b nt ,15vi3do m88eucooivr: x8as u. hydrochloric acid to produce an aqueous solution of zinc and chloridev ovmuo 3nx51rd8ie 8iua:s,oc .t8b5 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 hydrochloric acid in a2c3kcya6myejgizq3 . j mj-8* conical flask, the products are water, positive calcium ions and negative chj jammycye kgzq2j*c.3-386i loride ions.



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

  A bottle contains dilute ethanoic6l0. l2bt y.g :iqjwic 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 solution of a mono3kpll5+bw iz )vjf b52j-d4he protic weak zd wllpikvjb-e3)545 j2+ bhf acid?
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 resa5h+xes. 5g undb hl6+, k)msaction between sulphuric acid and+ k u5n,e)g5ds.hlh+sbx sm6a copper (II) 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 strxokhk-sn3 - 8n8bl:bq-hfdql 5 h6t3tong 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 of g;dbfy b)h8-ng g ):vxclassifying acids and bases.8b;gygb:nfd)hxg v) -
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, particularlges8 rjh2x1/z y glass such as windows. Theszexh218r gj /re 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 using the equ )x 3w:hw4dctsuvyja*00q2kdation below :ht* vdjcxqk423yuw)wd0as 0
$In + H_2O \rightleftharpoons InH^+ + OH^-;K_c = 35
Blue Yellow
Which of the below statements are correct?
I.The solution becomes darker blue with the addition of an acid
II.The solution is a pale green at equilibrium
III.$K_c$ increases with the addition of an alkali

In the amino acid glycine, a hydrogen ion 9sn3hf4qn: jn may be transferred from one part of the molecq jnfn:n49 hs3ule 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 aci5 0zvpjq b 5kh63zf3wpd-base pair?