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2 years ago

What is the change in entropy of the lead when 2.0 kg of molten lead at its melting point temperature solidifies.

1 answer:

7 0

Answer: The change in entropy of the lead when 2.0 kg of molten lead at its melting point temperature solidifies is 20 cal/K.

Explanation:

$Pb(l)\rightleftharpoons Pb(s)$

$\Delta S=\frac{q}{T}$

${\text{Change in entropy}}=\frac{heat}{Temperature}$

T is the temperature at which the process is carried out, here the temperature is constant, 327.5°C = $(273+327.5)K=600.5K$ ,because only phase change occurs.

q = heat given in the process = $m\times L_f$

m = mass of lead = 2.0 kg

$L_f$ = latent heat of fusion of lead = 5.9 kcal/kg

$\Delta S=\frac{2kg\times 5.9kcal/kg}{600.5K}$

$\Delta S=0.02 kcal/K=20cal/K$

Thus the change in entropy of the lead when 2.0 kg of molten lead at its melting point temperature solidifies is 20 cal/K.

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One of relatively few reactions that takes place directly between two solids at room temperature is In this equation, the in Ba(

yuradex [85]

Answer:

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate.

Explanation:

$Ba(OH)_2.8H_2O(s)+NH_4SCN(s)\rightarrow Ba(SCN)_2(s)+8H_2O(l)+NH_3(g)$

The balance chemical equation is :

$Ba(OH)_2.8H_2O(s)+2NH_4SCN(s)\rightarrow Ba(SCN)_2(s)+10H_2O(l)+2NH_3(g)$

Mass of barium hydroxide octahydrate = 6.5 g

Moles of barium hydroxide octahydrate = $\frac{6.5 g}{315 g/mol}=0.020635 mol$

According to reaction, 2 moles of ammonium thiocyanate reacts with1 mole of barium hydroxide octahydrate. The 0.020635 moles of barium hydroxide octahydrate will react with:

$\frac{2}{1}\times 0.020635 mol=0.04127 mol$

Mass of 0.04127 moles of ammonium thiocyanate;

$0.04127 mol\times 76 g/mol=3.136 g\approx 3.14 g$

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate

3 0

2 years ago

How can the knowledge of a material’s chemical makeup or use be utilized?

shutvik [7]

To identify minerals

Each material chemical makeup are a variety of chemical compounds which has each own category. They have different functional groups which helps people identify which material they look for. For instance, hydroxyl group has chemical makeup of alcohol

6 0

2 years ago

Read 2 more answers

What is the ph of a buffer prepared by adding 0.607 mol of the weak acid ha to 0.609 mol of naa in 2.00 l of solution? the disso

Paraphin [41]

Given:

0.607 mol of the weak acid

0.609 naa

2.00 liters of solution

The solution for finding the ph of a buffer:

[HA] = 0.607 / 2.00 = 0.3035 M
[A-]= 0.609/ 2.00 = 0.3045 M
pKa = 6.25

pH = 6.25 + log 0.3045/ 0.3035 = 6.25 is the ph buffer prepared.

6 0

2 years ago

Name the following cycloalkane:

KonstantinChe [14]

B is the correct answer

8 0

2 years ago

An organic synthesis to make the pain reliever acetaminophen is supposed to produce 280 kg of product but instead produces 70 kg

Irina-Kira [14]

Answer: 75%

Explanation:

The following information can be gotten from the question:

Waste = 70kg

Theoretical yield = 280kg

Therefore, the actual yield will be the difference between the theoretical yield and the waste which will be:

= 280kg - 70kg = 210kg

The percent yield will now be:

= Actual yield / Theoretical yield × 100

= 210/280 × 100

= 3/4 × 100

= 75%

4 0

2 years ago