Piv txwv ntawm Cov Lus Nug Sib Tham txog Kev daws teeb meem Stoichiometry
Stoichiometry yog ib ceg ntawm chemistry uas kawm txog kev sib raug zoo ntawm cov tshuaj reactants thiab cov khoom hauv cov tshuaj lom neeg. Cov tshuaj stoichiometry yog qhov tshwj xeeb dua, vim nws tsom mus rau cov tshuaj lom neeg uas tshwm sim hauv cov kuab tshuaj, feem ntau yog dej. Hauv tsab xov xwm no, peb yuav tham txog cov teeb meem piv txwv ntsig txog cov tshuaj stoichiometry kom nkag siab zoo dua txog lub tswv yim no.
Cov Ntsiab Lus Tseem Ceeb ntawm Kev daws teeb meem Stoichiometry
Ua ntej peb nkag mus rau hauv cov lus nug piv txwv, muaj qee lub ntsiab lus yooj yim uas peb yuav tsum nkag siab:
1. Molarity (M): Qhov concentration ntawm cov tshuaj yog qhia ua molarity. Molarity yog tus naj npawb ntawm moles ntawm solute ib liter ntawm cov tshuaj (mol/L).
2. Mol: Chav ntsuas ntawm qhov ntau ntawm cov khoom uas muaj Avogadro tus lej (6.022 x 10²³) cov khoom me me.
3. Qhov Ntim Tshuaj: Feem ntau ntsuas ua litres (L).
Nrog rau qhov kev nkag siab yooj yim no, peb npaj txhij los mus rau qhov piv txwv ntawm cov teeb meem thiab kev daws teeb meem.
Piv txwv lus nug 1: Xam Molarity ntawm ib qho kev daws teeb meem
Lo lus nug:
Muab hais tias 5 grams ntawm NaCl (Sodium Chloride) yaj rau hauv 250 mL dej, qhov molarity ntawm NaCl kua yog dab tsi?
Kev daws teeb meem:
1. Xam tus naj npawb ntawm moles ntawm NaCl:
– Qhov hnyav molecular (BM) ntawm NaCl: Na (23) + Cl (35.5) = 58.5 g/mol
- Tus naj npawb ntawm moles = Pawg / BM
“
Tus naj npawb ntawm moles ntawm NaCl = 5 g / 58.5 g/mol ≈ 0.0855 mol
“
2. Hloov qhov ntim ntawm cov kua los ntawm mL mus rau L:
“
Qhov ntim ntawm cov tshuaj = 250 mL = 0.250 L
“
3. Xam cov molarity (M):
“
Molarity (M) = Tus naj npawb ntawm moles / Ntim ntawm cov kua
= 0.0855 mol / 0.250 L
≈ 0.342 M
“
Yog li, molarity ntawm NaCl kua yog 0.342 M.
Piv txwv lus nug 2: Kev ua kom tsis muaj zog
Lo lus nug:
Yuav tsum muaj pes tsawg lub kua HCl 0.5 M kom tshem tau 50 mL ntawm 0.1 M NaOH kua?
Kev daws teeb meem:
Cov tshuaj tiv thaiv uas tshwm sim:
“
HCl + NaOH → NaCl + H₂O
“
Cov tshuaj tiv thaiv no tshwm sim hauv qhov sib piv 1: 1.
1. Xam tus naj npawb ntawm moles ntawm NaOH:
“
Tus naj npawb ntawm moles ntawm NaOH = Molarity x Ntim
= 0.1 M x 0.050 L
= 0.005 mol
“
2. Vim tias qhov sib piv ntawm cov tshuaj yog 1:1, tus naj npawb ntawm moles ntawm HCl = tus naj npawb ntawm moles ntawm NaOH = 0.005 mol.
3. Xam qhov ntim ntawm cov kua HCl uas xav tau:
“
Ntim ntawm HCl = Tus naj npawb ntawm moles / Molarity
= 0.005 mol / 0.5 M
= 0.01 L (los yog 10 mL)
“
Yog li, qhov ntim ntawm 0.5 M HCl kua yog 10 mL.
Piv txwv lus nug 3: Acid-Base Titration
Lo lus nug:
Siv 25 mL ntawm cov tshuaj CH₃COOH (acetic acid) titrated nrog 0.1 M NaOH kua mus rau qhov sib npaug. Yuav tsum tau 30 mL ntawm cov tshuaj NaOH kom mus txog qhov sib npaug. Xam cov molarity ntawm cov tshuaj CH₃COOH.
Kev daws teeb meem:
Cov tshuaj tiv thaiv uas tshwm sim:
“
CH₃COOH + NaOH → CH₃COONa + H₂O
“
Cov tshuaj tiv thaiv no kuj tshwm sim hauv qhov sib piv 1: 1.
1. Xam tus naj npawb ntawm cov moles ntawm NaOH siv:
“
Tus naj npawb ntawm moles ntawm NaOH = Molarity x Ntim
= 0.1 M x 0.030 L
= 0.003 mol
“
2. Tus naj npawb ntawm moles ntawm CH₃COOH yog tib yam li tus naj npawb ntawm moles ntawm NaOH uas tau ua haujlwm (piv 1:1):
“
Tus naj npawb ntawm moles ntawm CH₃COOH = 0.003 mol
“
3. Xam cov molarity ntawm CH₃COOH:
“
Molarity (M) = Tus naj npawb ntawm moles / Ntim
= 0.003 mol / 0.025 L
= 0.12 M
“
Yog li, molarity ntawm CH₃COOH kua yog 0.12 M.
Piv txwv lus nug 4: Kev sib tov ntawm cov tshuaj
Lo lus nug:
Yuav tsum ntxiv dej ntau npaum li cas los dilute 100 mL ntawm 1 M H₂SO₄ kua kom nws qhov concentration dhau los ua 0.25 M?
Kev daws teeb meem:
1. Siv cov mis dilution (M₁V₁ = M₂V₂):
– M₁ = 1 M
– V₁ = 100 mL
– M₂ = 0.25 M
2. Xam V₂:
“
M₁V₁ = M₂V₂
1 M x 100 mL = 0.25 M x V₂
V₂ = (1 x 100) / 0.25
= 400 ml
“
3. Xam qhov ntim dej uas yuav ntxiv rau:
“
Qhov ntim dej ntxiv = V₂ – V₁
= 400 mL – 100 mL
= 300 ml
“
Yog li, nws yog qhov tsim nyog los ntxiv 300 mL dej kom dilute cov tshuaj H₂SO₄ los ntawm 1 M mus rau 0.25 M.
Piv txwv lus nug 5: Kev cuam tshuam los ntawm nag lossis daus
Lo lus nug:
Thaum 100 mL ntawm 0.1 M AgNO₃ kua sib xyaw nrog 100 mL ntawm 0.1 M NaCl kua, muaj pes tsawg grams ntawm AgCl precipitate?
Kev daws teeb meem:
Cov tshuaj tiv thaiv uas tshwm sim:
“
AgNO₃ + NaCl → AgCl (ua kom nag lossis daus) + NaNO₃
“
Cov tshuaj tiv thaiv no tshwm sim hauv qhov sib piv 1: 1.
1. Xam tus naj npawb ntawm moles ntawm AgNO₃ thiab NaCl:
“
Tus naj npawb ntawm moles ntawm AgNO₃ = Molarity x Ntim
= 0.1 M x 0.100 L
= 0.01 mol
Tus naj npawb ntawm moles ntawm NaCl = Molarity x Ntim
= 0.1 M x 0.100 L
= 0.01 mol
“
2. Vim tias qhov sib piv ntawm cov tshuaj yog 1:1, tus naj npawb ntawm cov moles ntawm AgCl uas tau tsim = Tus naj npawb ntawm cov moles ntawm AgNO₃ lossis NaCl:
“
Tus naj npawb ntawm moles ntawm AgCl = 0.01 mol
“
3. Xam qhov hnyav ntawm AgCl:
- Qhov hnyav molecular ntawm AgCl = Ag (107.87) + Cl (35.45) = 143.32 g/mol
“
Qhov hnyav ntawm AgCl = Tus naj npawb ntawm moles x BM
= 0.01 mol x 143.32 g/mol
= 1.4332 g
“
Yog li, qhov hnyav ntawm AgCl precipitate tsim yog 1.4332 grams.
Xaus
Tsab xov xwm no tau tham txog ntau qhov piv txwv teeb meem thiab kev daws teeb meem hais txog kev daws teeb meem stoichiometry, suav nrog kev xam molarity, kev tsis sib haum xeeb, acid-base titrations, dilution, thiab precipitate tsim. Los ntawm kev nkag siab cov piv txwv no, peb tuaj yeem nkag siab zoo dua txog kev siv lub tswv yim ntawm kev daws teeb meem stoichiometry hauv cov xwm txheej tiag tiag. Kev daws teeb meem stoichiometry tsis yog tsuas yog tseem ceeb hauv kev kawm txog chemistry tab sis kuj muaj kev siv dav hauv ntau qhov chaw xws li tshuaj, biochemistry, thiab kev lag luam tshuaj lom neeg.
