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In aqueous solution, sulphuric acid dissociates into ions in 2 stages. The pKa for the first dissociation is -3. Calculate the pH of a 0.025 mol dm-3 solution of sulphuric acid using the pKa value of the 1st dissociation.

Ka = 10 -pKa = 10 --3 = 1000[H + ] = √ Ka [0.025] = √1000 x 0.025 = 0.791pH = -log [H] = -log(0.791) = 0.102 = 0.1
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Answered by Octavia M. • Chemistry tutor
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How do you form the perfect tense in German?

The perfect tense is a compound tense. This is because a sentence in the perfect tense is constructed from an auxiliary verb and a past participle.Let's use the simple sentence "I have played" as a...
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Answered by Tom G. • German tutor
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Express 280 as a product of its prime factors.

2 * 2 * 2 * 5 * 7 = 280
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Answered by Danny S. • Maths tutor
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Solve the simultaneous equations y = 5x^2 + 4x - 19 and y = 4x + 1

Okay, so for two simultaneous equations which both equal the same variable (in this example the variable they're equal to is y), the trick is to make both equations equal each other:so we can say that 4x + 1...
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Answered by Guy H. • Maths tutor
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How do I conjugate 're' verbs?

The way you can conjugate 're' verbs is to remember the specific endings for each pronoun: Je (I) - e Taking a common verb such as 'parler' we remove the 'er' and replace the endings for each pronoun :Tu (yo...
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Answered by Daniela C. • French tutor
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