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Chemistry / Chemie - 144
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| Which of the following combinations (where all weak components are in excess) can be used to produce a buffer solution? | Watter van die volgende kombinasies (waar alle swak komponente in oormaat is) kan gebruik word om 'n bufferoplossing te lewer? |
A chemist decides to prepare a buffer by adding 10.0 mL of 0.560 M NaOH to 50.0 mL of 0.140 M HClO. What is the pH of this buffer? (Ka(HClO) = 3.0 x 10-8) (Please provide your answer rounded off to 2 decimal places.) | 'n Chemikus besluit om 'n buffer voor te berei deur 10.0 mL van 0.560 M NaOH by 50.0 mL van 0.140 M HClO te voeg. Wat is die pH van hierdie buffer?(Ka(HClO) = 3.0 x 10-8) (Gee asb jou antwoord afgerond tot 2 desimale plekke.) |
The Ka of hypochlorous acid (HClO) is 3.0 x 10-8 at 25 °C. What is the pH of a 0.015 M aqueous solution of HClO at 25 °C? (Please provide your answer rounded off to 2 decimal places.) | Die Ka van hipochlorigsuur (HClO) is 3.0 x 10-8 by 25 °C. Wat is die pH van 'n 0.015 M waterige oplossing van HClO by 25 °C? (Gee asb jou antwoord afgerond tot 2 desimale plekke.) |
What is the pH of a buffer solution consisting of 1.00 g of HClO (Mr = 52.460 g.mol-1) and 1.00 g of NaClO (Mr = 74.442 g.mol-1) in a 1.00 L flask?(Ka(HClO) = 3.0 x 10-8) Please give your answer rounded off to 2 decimal places. | Wat is die pH van 'n buffer oplossing wat bestaan uit 1.00 g HClO (Mr = 52.460 g.mol-1) en 1.00 g NaClO (Mr = 74.442 g.mol-1) in 'n 1.00 L fles? (Ka(HClO) = 3.0 x 10-8) Gee asb jou antwoord afgerond tot 2 desimale plekke. |
| In step 4 of the diazepam synthesis, a methylation reaction takes place. A proposed mechanism is shown below. Study it and comment on any errors that you think have been shown. | In stap 4 van die diazepam-sintese vind 'n metieleringsreaksie plaas. 'n Voorgestelde meganisme word hieronder getoon. Bestudeer dit en lewer kommentaar op die foute wat jy sien. |
Suggest a method (i.e. a sequence of steps) that you would take in order to achieve step 1 of the synthesis of diazepam. You must:
| Stel 'n metode voor (dit wil sê 'n reeks stappe) wat jy sal neem om stap 1 van die sintese van diazepam te bereik. Jy moet:
|
A Vitamin C (ascorbic acid) tablet, with a mass of 5.137 g, was completely dissolved in water and made to volume in a 100 mL volumetric flask. A 0.0103 M NaOH solution was used to titrate against this ascorbic acid (C6H8O6) solution. The average (Volume NaOH/Volume C6H8O6) i.e. (Vb/Va) ratio at the endpoint was determined as 11.67. Determine the mass percentage of ascorbic acid in the original tablet. (Mr of ascorbic acid = 176.12 g/mol) The balanced reaction equation is given below. Please provide your answer rounded off to two decimal figures. | 'n Vitamien C (askorbiensuur) tablet, met 'n massa van 5.137 g, is volledig in water opgelos en in 'n volumetriese fles opgemaak tot 'n volume van 100 mL. 'n 0.0103 M NaOH oplossing is gebruik om teen hierdie askorbiensuur (C6H8O6) oplossing te titreer. Die gemiddelde (Volume NaOH/Volume C6H8O6) d.w.s. (Vb/Va) verhouding by die endpunt is vasgestel as 11.67. Bepaal die massapersentasie askorbiensuur in die oorspronklike tablet. (Mr askorbiensuur = 176.12 g/mol) Die gebalanseerde reaksievergelyking word hieronder gegee. Gee asseblief jou antwoord afgerond tot twee desimale syfers. |
| C6H8O6 (aq) + NaOH (aq) → C6H7O6Na (aq) + H2O (ℓ) |
| Identify the strong acids. | Identifiseer die sterk sure. |
| A 100.0 mL sample of acetic acid requires 100.0 mL of 0.100 M NaOH to reach the phenolphthalein end point (equivalence point) during a titration. What is the concentration of the conjugate base formed at the end point? | 'n 100.0 mL Monster van asynsuur benodig 100.0 mL van 0.100 M NaOH om die fenolftaleïen endpunt (ekwivalensiepunt) te bereik tydens ‘n titrasie. Wat is die konsentrasie van die gekonjugeerde basis wat gevorm het by die endpunt? |
Consider the pH titration between 50.0 mL 0.200 M acetic acid (Ka = 1.8 x 10-5, pKa = 4.74), and 100.0 mL of 0.100 M NaOH. What is the pOH of the solution at the endpoint? (Please give your answer rounded off to 2 decimal places.) | Oorweeg die pH-titrasie tussen 50.0 mL 0.200 M asynsuur (Ka = 1.8 x 10-5, pKa = 4.74) en 100.0 mL van 0.100 M NaOH. Wat is die pOH van die oplossing by die endpunt? (Gee asb jou antwoord afgerond tot 2 desimale plekke.) |