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3 years ago

How much energy moves onto the next level, in an energy pyramid

Chemistry

1 answer:

dybincka [34]3 years ago

7 0

10% is normally how it works .
For example like 1,000 is the top the next level would be 100 then the next would be 10

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Why doesn’t a broken wineglass spontaneously fix itself, from a thermodynamic point of view?

Anarel [89]

C. Fixing a wineglass requires a large decrease in entropy.

4 0

3 years ago

Read 2 more answers

A freezer compartment is covered with a 2-mm-thick layer of frost at the time it malfunctions. If the compartment is in ambient

ruslelena [56]

Answer:

The time required to melt the frost is 3.25 hours.

Explanation:

The time required to melt the frost dependes on the latent heat of the frost and the amount of heat it is transfered by convection to the air .

The heat transferred per unit area can be expressed as:

$q=h_c*A*\Delta T\\\\q/A=h_c*\Delta T$

being hc the convective heat transfer coefficient (2 Wm^-2K^-1) and ΔT the difference of temperature (20-0=20 °C or K).

$q/A=h_c*\Delta T=2\frac{W}{m^2K}*20K=40\frac{W}{m^2}$

If we take 1 m^2 of ice, with 2 mm of thickness, we have this volume

$V=T*A = 0.002 m * 1 m^2=0.002m^3$

The mass of the frost can be estimated as

$M=\rho * V=700\frac{kg}{m^3}*0.002m^3= 1.4 kg$

Then, the amount of heat needed to melt this surface (1 m²) of frost is

$Q=L*M=334\frac{kJ}{kg}*1.4kg= 467.6kJ$

The time needed to melt the frost can be calculated as

$t=\frac{Q}{(q/A)}=\frac{467.6kJ/m2}{40W/m2} = 11.69\frac{kJ}{W}*\frac{1W*s}{1J}*\frac{1000J}{1kJ}= 11690s=3.25h$

7 0

3 years ago

Identify the right

Basile [38]

.answer:

so the first one is analogous

the second is homologous

and the third is analogous

explanation:

analogous. this means they share a similar function (flight) but do not have the same embryonic origin.

6 0

3 years ago

What is the theoretical yield of fluorenone if you oxidize 175 mg of fluorene?

My name is Ann [436]

Answer:

602 mg of CO₂ and 94.8 mg of H₂O

Explanation:

The yield is measured by the amount of each product produced by the reaction.

The chemical formula of fluorene is C₁₃H₁₀, and its molar mass is 166.223 g/mol.

The oxidation, also know as combustion, of this hydrocarbon is represented by the following balanced chemical equation:

$2C_{13}H_{10}+31O_2\rightarrow 26CO_2+10H_2O$

To calculate the yield follow these steps:

1. Mole ratio

$2molC_{13}H_{10}:31molO_2:26molCO_2:10molH_2O$

2. Convert 175mg of fluorene to number of moles

$175mg/times 1g/1,000mg=0.175g$

Number of moles = mass in grams / molar mass

$\text{number of moles}=0.175g/166.223g/mol=0.0010528mol$

3. Set a proportion for each product of the reaction

a) For CO₂

i) number of moles

$2molC_{10}H_{13}/26molCO_2=0.0010528molC_{10}H{13}/x$

$x=0.0010528molC_{10}H_{13}\times 26molCO_2/2molC_{10}H_{13}=0.013686molCO_2$

ii) mass in grams

The molar mass of CO₂ is 44.01g/mol

mass = number of moles × molar mass

mass = 0.013686 moles × 44.01 g/mol = 0.602 g = 602mg

b) For H₂O

i) number of moles

$0.0010528molC_{10}H_{13}\times10molH_2O/2molC_{10}H_{13}=0.00526molH_2O$

ii) mass in grams

The molar mass of H₂O is 18.015g/mol

mass = number of moles × molar mass

mass = 0.00526 moles × 18.015 g/mol = 0.0948mg = 94.8 mg

4 0

3 years ago

Why do crisp packets become inflated at high altitudes? Again, explain in as great a detail as possible, using ideas about parti

Andrei [34K]

As you get higher the atmospheric pressure lowers. The pressure in the packet of crisps has the pressure at which it has been closed (pressure at the surface of the earth). This means that the air molecules in the packet press harder outside than the air molecules in the atmosphere press on the packet.

3 0

3 years ago