An example of a strong acid solution is nitric acid. Which sta xfos+j8)rf5a **jrey tement is correct forfjr x*f)85rsy*ejoa + this solution?

  Which of the following statements concerning acids and bases hb nx nsp3 2ela84:9 cpbr)fn4u+zos 5is not true?

  Which of the following is c cz c1q:+ yozp*a,:fno suzjry s3,o/k7jh;h:orrect?

  Which statement about a strong acid and its conjugate+xpk-ccag ke;vthb:o*;mh 7-)rm ns 7 base is correct?

  Which of the following expressivv5x04 s*f rlmg; m;kn1*p 7 yhaqsk5hons for $K_w$ is correct?

  Which combination of acid and base should be mg4hzrbe;x:mq jp;6 yyo ,m 3j4ma.: lreacted to obtain a basic salt?

  A reaction produces carbon dioxide gas and a;qz rsl bo+mp7gvh)8+ solution of water with a dissolved saltszo;) 7vqph+rmg8bl+ . What could be the reactants?

  Which combination of acid and base will typically have thjj+877 b sfh8,s veeqae lowest pH at the equivalence point i87, qj8 sbhsevj7f+e an a titration?

  In order to prepare a solb50-qp./h oe2dnr xlqution of $0.1mol\:dm^{-3}$ with the highest pH, substance XX is dissolved in water. Substance X is

  Water dissociates partially and typb( * e.nw4p7hqdf+ uhe value of the ionic product constant of watern*p +bhq(.4 u7f ypwde 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 converted to ethanoic acid. Tp 2x-c ri4lr8kbtv5stx77cc 6he \ce{pH}pH of a bottle of wine changes from 6.5 to 4.5.7c kv5cr4rlcp 8xt-x6ib7 s2t The concentration of $[H]^+$ is?

  A molecule of HBr reactw.8xxc8,vm *i ady:i b*z9cey/b) rzss with water to produce the charged molecule X. What is the Lewis struc9yzmdbb .iv)y:,ixre8/c wa 8zx**csture of molecule X?

  Alkali solutions can be made by dissolving a basic substanc.d f/;1 kv8.ay bsdqvne 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 9(e pd-v7nw9xehi 9 izof nitric 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 followitn18l,6wmkz7n0:ux rt- t cvnng 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 indicators are corrb0z;ansr5aivh i+c - 5ect?
|.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 represea6 4hqvyw5tl5 96mlnv7fmts3x1 vg 5w-h 7vvents $K_a$ for $CH_3COOH$?

  Given the following indicators and their behaviours, what will bes6tydq63jv*b g0l e5t the correct colours of a solution of 1.0ve3l*qg jt6by6s5 d0t 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 ao n;3 u0jdfsr k.3;rsacid 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 ep ;2f9m*fe as+itr x*2bp1xt59 oagyphosphate 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 p6twwbvp-wmwv:m .o5-dy) , l $1.0\,mol\:dm^{-3}$ solutions in order of increasing pH:
$NaOH,Na_2CO_3,NaCl$

  Which of the following reactions is not a neutralizw70 sk-u gj)vmr9 xay*ation reaction?

One example of an importary (xr :j7xr5lzfj 0p6nt 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 between dka2c) f/r;fl $NH_3$ 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 54n+ xwadpps88cx z q*$0.001\,mol\,dm^{-3}$ aqueous solution of KOH at 298K given that it ionizes completely?

Consider the following rea7e5,an14 w hm.titkxsction:
$H_2SO_4(aq) + NH_3(aq) \rightleftharpoons HSO_4^-(aq) + NH^+_4(aq)$
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 concxlq;)+ycfs6)f vlxq8 entrations, form)f ;6fxq+ )llvy8qscx 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 acid when it reacts wit 0drccg+.e f :(yv-6fc7cznt nh 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 c)ktd7yy oy;b7 mq+d 2hydroxide antydo77 kqd+ ;bym2)cy d ethanoic acid?

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

  Which statements are cpax 4p* q)gy5vorrect?
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 ah2t39 vt x7umbc0k ,6erb bqam,x yb,2cid.
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 6q 3j/x4.tcsulwwp8rof acid-base titrations is incorrect?lp 43s8 j/rw6wc xt.qu

  Which of the following sal nez( c)0vrub;ts form basic solutions when dissolved in water?
I.$NH_4Cl$
II.$K_2CO_3$
III.$NaOOCCH_3$

  Which of the following combina2 :w-tgjgs/lmhugf4b14 e vr 9mhl7:d tions of $NH_3(aq)$ and HCl(aq) forms a buffer solution?

  The correct sequence in decreasing order of pH for equimol)ffwuldhm 9s e9f ;4s)ar solutions is:

  Which of the three oxides of period 3 belookx 19 6cwm5/na ke.azw will cause a change in the pH of the solut e 9k5 /oxaw1k.a6mcznion when they react with water?
I.$Na_2O$
II.$SiO_2$
III.$P_4O_{10}$

1. 1.Differentiate between a strong acid and a weak 2m2:fo vlid4m 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 irxhum2+,0m9 .u h t0+swflvj $HNO_3$ 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 iw k r dx(9daoq:;(o1zqs incorrect?

Ethanoic acid reacts with trimethylamine to produce a negatively charged etha0 ).w pszz,ry.u1,fdg h b5pfpnoate ion and another charged compound X1.z,pfz0p .g5dyr ws up)h,bf.


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 anpd6 f/ -x;ucsre correctly matched with the salt formed from their;s/xnpcf- u d6 reaction?

This question is about the weak acid, w;ql y lh: 4xj:ivn h :0eq0ace5f;lu*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 th qb yjxr:hr-/q 40kwk)e 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 percentam0) d9ykma gq7ge of ethanoic acid. A student wishes to determine the concentration of ethanoic acid in vinegar. She titrates a solution of g7dm )0ykamq9 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 according to+3*; ff.xo wudqybrd0 the Bronsted-Lf oyd 0x.+wb3;drfuq* owry theory?

Zinc(II) oxide reacts with hydrochloric acid to produce ay 9 muge:bcak,8hd;8sr(8h j an aqueous solution of zinc 9s hug(a; :b8y 8rhdcka8,ejm 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 dilute hydrochloric acid i63 kbetzkio18bawfi+c(u x;*,1gstwn a conical flask, the e;k*a1z1 ic,+3g6tbi8w w (kfxbutso 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 ethano94tjg0a ddz/w jcc8:w bo: ao)ic 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 requinjfpw -zx8gih*h;g4;;x dna. red to calculate the pH of a solution of a monoprotic weak acidpzanf4 hj;g;-;gwd x 8.x*ihn?
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 sulphu0oztj6l8aj go09y emkh02ize 4 -f-kg ric acid and copper (II) oxid ogjih04folz mye09eg-kt 2jk z680a-e.
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 oriq0pj3 izu g8oml.-v1 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 Lewicu y;- ;xt7lyus theories are two different theories of classifying aciduulyc ;;y-7txs 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 hwgjnh ;5( hzy 54j5hdcouses, particularly glass such as windows. There are many safety wa5h njgw5j d;ch54h (yzrnings 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 ie xdi vj25yg:+ndicator, In, can be expressed using the equation below veyj 5i:2g+xd
$In + H_2O \rightleftharpoons InH^+ + OH^-;K_c = 35
Blue Yellow
Which of the below statements are correct?
I.The solution becomes darker blue with the addition of an acid
II.The solution is a pale green at equilibrium
III.$K_c$ increases with the addition of an alkali

In the amino acid glyctfm1 c4jnfk6a9cxc c 67s-n,g ine, a hydrogen ion may be transferred from one part of the molecule to another as showm1sj cat46c6c n7f x-gk9 fcn,n.



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-bas wv22r, a3 kkg0hzu2zwe pair?