Mehlala ea Lipotso Tse Buisanang ka Matla le pH ea Li-acid le Metheo
Matla a motheo oa asiti le pH ke lihlooho tsa bohlokoa k'hemistri, haholo-holo lefapheng la li-acid le li-base. Sehloohong sena, re tla buisana ka mokhoa oa ho fumana matla a asiti le a motheo le ho bala pH ea tharollo re sebelisa mehlala e 'maloa ea mathata.
Selelekela ho Acids le Bases
Assam
Asiti ke motsoako o ka lokollang li-ion tsa haedrojene (H⁺) ha o qhibiliha ka metsing. Ho latela bokhoni ba tsona ba ho lokolla li-ion tsa H⁺, li-acid li arotsoe ka mefuta e 'meli:
1. Asiti e matla: Asiti e arolang 100% tharollong, e lokollang li-ion tsa H⁺ ka botlalo. Mehlala: Asiti ea Hydrochloric (HCl), asiti ea sulfuric (H₂SO₄), asiti ea nitric (HNO₃).
2. Asiti e fokolang: Asiti e arohanang hanyane feela tharollong, ke limolek'hule tse ling feela tse lokollang li-ion tsa H⁺. Mehlala: Asiti ea Acetic (CH₃COOH), asiti ea carbonic (H₂CO₃), asiti ea hydrocyanic (HCN).
motheo
Motheo ke motsoako o ka lokollang li-ion tsa hydroxide (OH⁻) ha o qhibiliha ka metsing. Ho latela bokhoni ba tsona ba ho lokolla li-ion tsa OH⁻, li-base le tsona li arotsoe ka mefuta e 'meli:
1. Motheo o matla: Motheo o arolang 100% tharollong, o lokolla li-ion tsa OH⁻ ka botlalo. Mehlala: Sodium hydroxide (NaOH), potassium hydroxide (KOH).
2. Motheo o fokolang: Motheo o arohanang ka karolo feela tharollong, ke limolek'hule tse ling feela tse lokollang li-ion tsa OH⁻. Mehlala: Ammonia (NH₃), magnesium hydroxide (Mg(OH)₂).
Khopolo ea pH
pH ke tekanyo ea asiti kapa alkalinity ea tharollo. E hlalosoa e le logarithm e mpe ea mahloriso a hydrogen ion (H⁺):
\[ \text{pH} = – \log [H⁺] \]
Bakeng sa ditharollo tsa motheo, pOH le yona e a sebediswa, e hlaloswang e le logarithm e mpe ya mahloriso a ion ya hydroxide (OH⁻):
\[ \text{pOH} = – \log [OH⁻] \]
Kamano pakeng tsa pH le pOH ke:
\[ \mongolo{pH} + \mongolo{pOH} = 14 \]
pH ea 7 e bitsoa e sa nke lehlakore, pH e ka tlase ho 7 e na le asiti, 'me pH e fetang 7 e na le alkaline.
Lipotso tsa Mehlala le Puisano
Mohlala oa Potso ea 1: Ho bala pH ea Asiti e Matla
Potso: Fumana pH ea tharollo ea 0,01 M HCl.
Puisano: HCl ke asiti e matla e tla arohana ka ho feletseng ho ba li-ion tsa H⁺ le Cl⁻. Kaha e na le molarity ea 1:1 pakeng tsa HCl le H⁺, mahloriso a H⁺ ke 0,01 M.
\[ \text{pH} = – \log [H⁺] \]
\[ \mongolo{pH} = – \log (0,01) \]
\[ \mongolo{pH} = 2 \]
Kahoo, pH ea tharollo ea 0,01 M HCl ke 2.
Mohlala oa Potso ea 2: Ho bala pH ea Asiti e Fokolang
Potso: Fumana pH ea tharollo ea 0,1 M CH₃COOH (acetic acid) haeba \( K_a \) ea CH₃COOH e \( 1,8 \makhetlo a 10^{-5} \).
Puisano: Li-acid tse fokolang ha li arohane ka ho feletseng, kahoo re sebelisa mokhoa o sa fetoheng oa ho arohana ha asiti ( \( K_a \) ) ho fumana hore na H⁺ e na le mahloriso a bokae. Bakeng sa CH₃COOH, equation ea ho arohana ke:
\[ \text{CH₃ COOH} \rightleftharpoons \text{H⁺} + \text{CH₃ COO⁻} \]
Ho latela molao oa tharollo ea buffer, re nahana hore \( x \) ke mahloriso a li-ion tsa H⁺ tse entsoeng:
\[ K_a = \frac{ [H⁺][CH₃ COO⁻] }{ [CH₃ COOH] } \]
\[ 1,8 \makgetlo a 10^{-5} = \frac{ (x)(x) }{ 0,1 – x } \]
Kaha \( x \) e nyane haholo ha e bapisoa le 0,1 M, re ka hlokomoloha x ho denominator:
\[ 1,8 \makgetlo a 10^{-5} \hoo e ka bang \frac{ x^2 }{ 0,1 } \]
\[ x^2 \hoo e ka bang 1,8 \makgetlo a 10^{-6} \]
\[ x \hoo e ka bang \sqrt{ 1,8 \makgetlo a 10^{-6} } \]
\[ x \hoo e ka bang 1,34 \makgetlo a 10^{-3} \]
Kahoo, mahloriso a H⁺ ke \( 1,34 \times 10^{-3} \):
\[ \text{pH} = – \log [H⁺] \]
\[ \text{pH} = – \log (1,34 \makgetlo a 10^{-3}) \]
\[ \text{pH} \hoo e ka bang 2,87 \]
Kahoo, pH ea tharollo ea 0,1 M CH₃COOH e ka ba 2,87.
Mohlala oa Potso ea 3: Ho bala pH ea Motheo o Matla
Potso: Fumana pH ea tharollo ea 0,01 M NaOH.
Puisano: NaOH ke motheo o matla o tla arohana ka ho feletseng le li-ion tsa Na⁺ le OH⁻. Kaha e na le molarity ea 1:1 pakeng tsa NaOH le OH⁻, mahloriso a OH⁻ ke 0,01 M.
\[ \text{pOH} = – \log [OH⁻] \]
\[ \text{pOH} = – \log (0,01) \]
\[ \mongolo{pOH} = 2 \]
Ho sebedisa kamano \( \text{pH} + \text{pOH} = 14 \):
\[ \mongolo{pH} = 14 – \mongolo{pOH} \]
\[ \mongolo{pH} = 14 – 2 \]
\[ \mongolo{pH} = 12 \]
Kahoo, pH ea tharollo ea NaOH ea 0,01 M ke 12.
Mohlala oa Potso ea 4: Ho bala pH ea Motheo o Fokolang
Potso: Fumana pH ea tharollo ea NH₃ ea 0,1 M haeba \( K_b \) ea NH₃ e \( 1,8 \makhetlo a 10^{-5} \).
Puisano: Metheo e fokolang ha e arohane ka ho feletseng, kahoo re sebelisa mokhoa o sa fetoheng oa karohano ea motheo ( \( K_b \) ) ho fumana hore na OH⁻ e hokahane hakae. Bakeng sa NH₃, equation ea karohano ke:
\[ \text{NH₃ + H₂O} \rightleftharpoons \text{NH₄⁺ + OH⁻} \]
Ha re sebelisa mokhoa o tšoanang le oa li-acid tse fokolang, re nahana hore \( y \) ke mahloriso a li-ion tsa OH⁻ tse entsoeng:
\[ K_b = \frac{ [NH₄⁺][OH⁻] }{ [NH₃] } \]
\[ 1,8 \nako 10^{-5} = \frac{ (y)(y)}{ 0,1 – y } \]
Ha re nahana hore \( y \) e nyane, equation e ba:
\[ 1,8 \makgetlo a 10^{-5} \hoo e ka bang \frac{ y^2 }{ 0,1 } \]
\[ y^2 \hoo e ka bang 1,8 \makgetlo a 10^{-6} \]
\[ y \hoo e ka bang \sqrt{ 1,8 \makgetlo a 10^{-6} } \]
\[ y \hoo e ka bang 1,34 \makgetlo a 10^{-3} \]
Khakanyo ea OH⁻ ke \( 1,34 \times 10^{-3} \):
\[ \text{pOH} = – \log [OH⁻] \]
\[ \text{pOH} = – \log (1,34 \makgetlo a 10^{-3}) \]
\[ \text{pOH} \hoo e ka bang 2,87 \]
Ho sebedisa kamano \( \text{pH} + \text{pOH} = 14 \):
\[ \mongolo{pH} = 14 – 2,87 \]
\[ \text{pH} \hoo e ka bang 11,13 \]
Kahoo, pH ea tharollo ea NH₃ ea 0,1 M e ka ba 11,13.
Qetello
Ho fumana pH ea tharollo le ho utloisisa matla a li-acid le li-base ke metheo ea bohlokoa k'hemistring. Li-acid le li-base tse matla li arohana ka ho feletseng tharollong, ha li-acid le li-base tse fokolang li arohana ka karolo e itseng feela. Ho sebelisa \( K_a \) le \( K_b \) ho etsa hore ho be bonolo ho bala pH ea li-acid le li-base tse fokolang. Bokhoni bona bo bohlokoa bakeng sa lits'ebetso masimong a fapaneng, ho kenyeletsoa le k'hemistri ea indasteri, ea meriana le ea tikoloho. Ka ho utloisisa likhopolo le ho ithuta mehlala, re ka rarolla mathata a amanang le pH le matla a acid-base bophelong ba letsatsi le letsatsi habonolo.
