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Anvisha [2.4K]
3 years ago
13

Which of the pairs below would be the best choice for a pH 5 buffer? HF/NaF, K a (HF) = 3.5 × 10-4 HC2H3O2/KC2H3O2, K a (HC2H3O2

) = 1.8 × 10-5 NH3/NH4Cl, K b (NH3) = 1.8 × 10-5
Chemistry
1 answer:
kati45 [8]3 years ago
3 0

Answer:

HC₂H₃O₂/KC₂H₃O₂

Explanation:

Considering the Henderson- Hasselbalch equation for the calculation of the pH of the basic buffer solution as:


pH=pK_b+log\frac{[salt]}{[acid]}


For a best pair, the pKa value must be equal to pH.

NH₃/NH₄Cl forms a basic buffer and cannot account for pH = 5

out of the acidic buffer given,

So, HF , Ka = 3.5 × 10⁻⁴ , So pKa = 3.46

HC₂H₃O₂ , Ka = 1.8 × 10⁻⁵ , So pKa = 4.77

<u>The best pair to show pH = 5 is HC₂H₃O₂/KC₂H₃O₂</u>

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What is the maximum amount of CO2
Wittaler [7]

Answer:

10.6 g CO₂

Explanation:

You have not been given a limiting reagent. Therefore, to find the maximum amount of CO₂, you need to convert the masses of both reactants to CO₂. The smaller amount of CO₂ produced will be the accurate amount. This is because that amount is all the corresponding reactant can produce before it runs out.

To find the mass of CO₂, you need to (1) convert grams C₂H₂/O₂ to moles (via molar mass), then (2) convert moles C₂H₂/O₂ to moles CO₂ (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles CO₂ to grams (via molar mass). *I had to guess the chemical reaction because the reaction coefficients are necessary in calculating the mass of CO₂.*

C₂H₂ + O₂ ----> 2 CO₂ + H₂

9.31 g C₂H₂            1 mole               2 moles CO₂          44.0095 g
------------------  x  -------------------  x  ----------------------  x  -------------------  =
                            26.0373 g           1 mole C₂H₂              1 mole

=  31.5 g CO₂

3.8 g O₂             1 mole               2 moles CO₂          44.0095 g
-------------  x  --------------------  x  ----------------------  x  --------------------  =
                       31.9988 g              1 mole O₂                 1 mole

=  10.6 g CO₂

10.6 g CO₂ is the maximum amount of CO₂ that can be produced. In other words, the entire 3.8 g O₂ will be used up in the reaction before all of the 9.31 g C₂H₂ will be used.

8 0
2 years ago
If energy increasing or decreasing as you go from a solid to a liquid
Gelneren [198K]
The energy increases because the molecules in water move faster
8 0
3 years ago
Read 2 more answers
What is the maximum amount of HCl, in grams, that can be produced if 37.5 g of BCl3 and 60.0 g of H2O are reacted according to t
Rus_ich [418]
Ooooh boy alright. So, this may or may not be a limited reactant problem so we need to first find out of it is.

First, how many moles of each substance are there

the molar mass of BCl3 is <span>117.17 grams so 37.5 g / 117.17 is ~ .32 mol.
The molar mass of H2O is 18.02 so 60 / 18.02 is ~ 3.33 mol.

Now, for every 1 mole of BCl3, there are 3 moles of HCl created. Therefore, BCl3 can create ~ .96 moles.
For every 3 moles of H2O, there are 3 moles of HCl created. Therefore, HCl can create ~3.33 moles.

But, there is not enough BCl3 to support that 3.33 moles, only enough for .96 moles, therefore BCl3 is the limiting reactant. Now, to answer the question, simply multiply .96 moles by the molar mass of HCl.

.96 x 36.46 = ~35 g</span>
6 0
3 years ago
Describe how you could use two LB/agar plates, some E. coli, and some ampicillin to determine how E. coli cells are affected by
KiRa [710]

Answer:

For this experiment we are going to take plate 1 as the control plate, so, in it there will be just E. coli in LB/agar; in plate 2, we are going to put E. coli in LB/agar and some ampicillin.  Then, we have to wait for the E. coli colonies to form. After a while, the E. coli growth can be compared on both plates and determine if ampicillin affects or not the E. coli colonies.

Explanation:

If the ampicillin affects negatively E. coli colonies, we are going to observe that in plate 1 (control plate) there are E. coli colonies growing, but in plate 2, there is no E. coli colonies or, at least, there is a fewer number of colonies on it. If ampicillin doesn't affect E.coli, plate 1 (control) and plate 2 (ampicillin experiment) are going to be similar in number of colonies.

8 0
3 years ago
Calculate the freezing point of a solution that contains 8.0 g of sucrose (C12H22O11) in 100 g of H2O. Kf for H2O = 1.86C/m
Aleks04 [339]

The freezing point of the sucrose solution is -0.435°C.

<h3>What is the freezing point of the solution?</h3>

The freezing point of the solution is determined from the freezing point depression formula below:

  • ΔT = mKf(H₂O)

Kf(H₂O) = 1.86 Cm

m is molality of solution = moles of solute/mass of solvent

moles of sucrose = 8.0/342.3 = 0.0233 moles

m = 0.0233/0.1 = 0.233 molal

ΔT = 0.233 m * 1.86°C/m.

ΔT = 0.435 °C.

Freezing point of sucrose solution = 0°C - 0.435°C

Freezing point of sucrose solution  = -0.435°C.

In conclusion, the freezing point of sucrose solution is determined from the freezing point depression.

Learn more about freezing point depression at: brainly.com/question/19340523

#SPJ1

8 0
2 years ago
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