Chemistry, 23.07.2019 16:30, heavyhearttim

How many grams of dry nh4cl need to be added to 1.60 l of a 0.600 m solution of ammonia, nh3, to prepare a buffer solution that has a ph of 8.54? kb for ammonia is 1.8×10−5?

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NH4 is the conjugate base for NH3. You will need to calculate pKa for NH4. Then you can use the Henderson Hasselbalch equation to find the concentration ration [base]/[acid]. Once you know the ratio, you can determine the required molar concentration of the salt and then calculate the mass of the salt. Calculate pKa for NH4 Kb is 1.8x10^-5, where Ka*Kb=Kw Ka = 1.0x10^-14/(1.8x10^-5) Ka = 5.5x10^-10 pka = 9.26 Calculate the ration of base to acid using the HH equation and rearrange to have [base]/[acid] by its self. 8.98=9.26 + log[base]/[acid] [base]/[acid]= 0.52 Since the pH of the biffer is less than pKa that means the buffer should contain more acid than base. The ratio of base to acid is less than 1, which is in agreement with that expectation. so now calculate the concentration of NH4 [NH3]/[NH4] =0.52 Concentration of NH3 is 0.600M [NH4]=0.600/0.52 = 1.15 M Now that you know the CONCENTRATION and have VOLUME, you now solve for moles (re: C= n/V) moles = 2.19mols and using molar mass of 53.5g/mol... mass = 117.165 grams of NH4Cl

answered: Guest

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

answered: Guest

c, liquids evaporate, creating a gas

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How many grams of dry nh4cl need to be added to 1.60 l of a 0.600 m solution of ammonia, nh3, to pre...