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3 years ago

Steel cranes can carry heavy steel beams thousands of feet high during skyscraper construction. This is an example of:

Chemistry

2 answers:

Ronch [10]3 years ago

6 0

The evolution of building techniques is your answer

Because building techniques become better, because of technology and better materials, we can now build steel cranes that can carry heavier things

hope this helps

beks73 [17]3 years ago

4 0

Hello!

The steel cranes lifting thousands of feet high during skyscraper construction is an example of the evolution of building techniques.

I hope it helps!

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If a pork roast must absorb kJ to fully cook, and if only 10% of the heat produced by the barbecue is actually absorbed by the r

kolezko [41]

Answer:

1,033.56 grams of carbon dioxide was emitted into the atmosphere.

Explanation:

$C_3H_8(g)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(g),\Delta H_{rxn}=-2044 kJ/mol (assuming)$

Energy absorbed by pork,E = $1.6\times 10^3 kJ$ (assuming)

Total energy produced by barbecue = Q

Percentage of energy absorbed by pork = 10%

$10\%=\frac{E}{Q}\times 100$

$Q=\frac{E}{10}\times 100=\frac{1.6\times 10^3 kJ}{10}\times 100=1.6\times 10^4 kJ$

Since, it is a energy produced in order to indicate the direction of heat produced we will use negative sign.

Q = $-1.6\times 10^4 kJ$

Moles of propane burnt to produce Q energy =n

$n\times \Delta H_{rxn}=Q$

$n=\frac{Q}{\Delta H_{rxn}}=\frac{-1.6\times 10^4 kJ}{-2044 kJ/mol}=7.83 mol$

According to reaction , 1 mol of propane gives 3 moles of carbon dioxide. then 7.83 moles of will give:

$\frac{1}{3}\times 7.83 mol=23.49 mol$ carbon dioxide gas.

Mass of 23.49 moles of carbon dioxide gas:

23.49 mol × 44 g/mol =1,033.56 g

1,033.56 grams of carbon dioxide was emitted into the atmosphere.

8 0

2 years ago

For the Earth's atmosphere, section number two in the pie graph BEST represents the percentage of A) argon B) oxygen C) nitrogen

larisa86 [58]

-Oxygen

According to Google these are the percentages of the Earths Atmosphere

1 78% - Nitrogen

2 21% - Oxygen

3 0.9% - Argon

4 0.3 - Carbon Dioxide with very small percentage of other elements.

3 0

3 years ago

What is the noble gas electron configuration of bismuth (Bi)? A. [Kr] 6s2 6p3 B. [Xe] 6s2 6p3 C. [Xe] 4f14 5d10 6s2 6p3 D. [Kr]

OlgaM077 [116]

The answer is C) Xe 4f14 5d10 6s2 6p3

4 0

3 years ago

Read 2 more answers

A box has a weight of 120 lbs and the bottom of the box is 12 in2 . What is the pressure the box exerts on the floor?

denis23 [38]

How can I help with this question?

7 0

3 years ago

2KClO3(s) => 2KCl(s) + 3O2(g) is there an increase or decrease of entropy?

ValentinkaMS [17]

Answer:

Entropy increases

Explanation:

Entropy (S) is a measure of the degree of disorder. For a given substance - say water - across phases the following is true ...

S(ice) < S(water) << S(steam)

For a chemical process, entropy changes can be related to increasing or decreasing molar volumes of gas from reactant side of equation to product side of equation. That is ...

if molar volumes of gas increase, then entropy increases, and

if molar volumes of gas decrease, then entropy decreases.

For the reaction 2KClO₃(s) => 2KCl(s) + 3O₂(g)

molar volumes of gas => 0Vm* 0Vm 3Vm

*molar volumes (Vm) apply only to gas phase substances. Solids and liquids do not have molar volume.

Since the reaction produces 3 molar volumes of O₂(g) product vs 0 molar volumes of reactant, then the reaction is showing an increase in molar volumes of gas phase substances and its entropy is therefore increasing.

3 0

3 years ago