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3 years ago

Which property of water best explains why ice forms on its surface

1 answer:

5 0

The hydrogen bonding tendency of water causes it to be 'sticky,' in that water molecules tend to stick together (as in a puddle). This is known ascohesion. Because of this property, water has a high surface tension. This means that it takes a little extra force to break the surface of the water puddle.Mar 13, 2018

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Find the pH of the equivalence point and the volume (mL) of 0.0372 M NaOH needed to reach the equivalence point in the titration

elixir [45]

Answer:

8.54

Explanation:

At equivalence point :

42.2 X 0.052 = Vol. NaOH X 0.0372

Vol of NaOH = 2.1944/0.0372 = 58.99 ml

So volume of NaOH recquired to reach equivalence point = 58.99 ml

Number of miliimoles of CH3COOH = molarity X volume in ml = 42.2 X 0.052 = 2.1944 millimoles

Number of millimoles of NaOH = 58.99 X 0.0372 = 2.1944

Now CH₃COOH and NaOH reacts to give CH₃COONa according to the reaction :

CH₃COOH + NaOH ------> CH₃COONa + H₂O

1 mole of CH₃COOH reacts with 1 mole of NaOH to give 1 mole of CH₃COONa

So 2.1944 millimoles of CH₃COOH will react with 2.1944 millimoles of NaOH to give 2.1944 millimoles of CH₃COONa

So all the acid (CH₃COOH) and base (NaOH) has been converted into salt (CH₃COONa) so there is no acid or base left.

Now molarity of CH₃COONa = number of millimoles of CH₃COONa/total volume in ml = 2.1944/(58.99 + 42.2) = 2.1944/101.19 = 0.02169 M

So using the hydrolysis equation :

pH = 1/2 [ pKw + pKa + log c ]

Ka for acetic acid = 1.75 X 10⁻⁵

so pKa = -log (1.75 X 10⁻⁵) = 4.74

Kw = 10⁻¹⁴

so pKw = -log 10⁻¹⁴ = 14

c = 0.02169

so log c = log 0.02169 = -1.66

putting the values....

pH = 1/2 [14 + 4.74 - 1.66 ]

pH = 1/2 [ 17.08] = 8.54

6 0

3 years ago

Read 2 more answers

POS MOLECULES SPEED UP WHEN ENERGY IS CREATED AND SLOW DOWN WHEN ENERGY IS DESTROYED True False? explain why

Colt1911 [192]

Answer: Scientists use the term bioenergetics to describe the concept of energy flow (Figure 4.2) through living systems, such as cells. Cellular processes such as the building and breaking down of complex molecules occur through stepwise chemical reactions. Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed. Just as living things must continually consume food to replenish their energy supplies, cells must continually produce more energy to replenish that used by the many energy-requiring chemical reactions that constantly take place. Together, all of the chemical reactions that take place inside cells, including those that consume or generate energy, are referred to as the cell’s metabolism.

5 0

2 years ago

There are seven types of crystals. Which of these is not one of the seven?

Gelneren [198K]

The answer is B. tetraclinic

3 0

2 years ago

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an engineering team is conducting a trial launch of a few rocket . which part is the engineering process is the team in ?

brilliants [131]

Answer:

Evaluate the result (Apex)

Explanation:

7 0

3 years ago

Calculate the vapor pressure of water at T=90°C

LenKa [72]

The equilibrium vapour pressure is typically the pressure exerted by a liquid .... it is A FUNCTION of temperature...

Explanation:

By way of example, chemists and physicists habitually use

saturated vapour pressure

...where

SVP

is the vapour pressure exerted by liquid water. At

100

∘

SVP

⋅

. Why?

Well, because this is the normal boiling point of water: i.e. the conditions of pressure (i.e. here

⋅

) and temperature, here

100

∘

, at which the VAPOUR PRESSURE of the liquid is ONE ATMOSPHERE...and bubbles of vapour form directly in the liquid. As an undergraduate you should commit this definition, or your text definition, to memory...

At lower temperatures, water exerts a much lower vapour pressure...but these should often be used in calculations...especially when a gas is collected by water displacement. Tables of

saturated vapour pressure

are available.

4 0

3 years ago