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2 years ago

What could reduce the heat island effect around cities?

Chemistry

1 answer:

melamori03 [73]2 years ago

5 0

Answer: (D.) Planting Roof gardens

Explanation: I'm really hoping you get this right but the reason of my answer is because Trees, green roofs, and vegetation can help reduce urban heat island effects by shading building surfaces, deflecting radiation from the sun, and releasing moisture into the atmosphere.

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How many moles of HBr are present in 250 ml of a 0.15 M HBr solution?

Fofino [41]

Answer:

0.0375 moles HBr

Explanation:

we are given;

Molarity of HBr solution as 0.15 M
Volume of the solution as 250 mL

We are required to determine the number of moles;

We need to know that;

Molarity = Moles ÷ Volume

Therefore;

Moles of HBr = Molarity of HBr solution × Volume of solution

Thus;

Moles of HBr = 0.15 M × 0.25 L

= 0.0375 Moles

Thus, the number of moles of HBr solute is 0.0375 moles

6 0

3 years ago

What is the associated deBroglie wavelength of a H2 molecule moving on one direction with kinetic energy of (3/2 kT) at 30 K

andrey2020 [161]

<u>Answer:</u> The de-Broglie's wavelength of a hydrogen molecule is $3.26\AA$

<u>Explanation:</u>

Kinetic energy is the measure of temperature of the system.

The equation used to calculate kinetic energy of a particle follows:

$E=\frac{3}{2}kT$

where,

E = kinetic energy of the particles = ?

k = Boltzmann constant = $1.38\times 10^{-23}J/K$

T = temperature of the particle = 30 K

Putting values in above equation, we get:

$E=\frac{3}{2}\times 1.38\times 10^{-23}J/K\times 30K\\\\E=6.21\times 10^{-22}J$

Calculating the mass of 1 molecule of hydrogen gas:

Conversion factor used: 1 kg = 1000 g

1 mole of hydrogen gas has a mass of 2 grams or $2\times 10^{-3}kg$

According to mole concept:

$6.022\times 10^{23}$ number of molecules occupy 1 mole of a gas.

As, $6.022\times 10^{23}$ number of hydrogen molecules has a mass of $2\times 10^{-3}kg$

So, 1 molecule of hydrogen will have a mass of = $\frac{2\times 10^{-3}kg}{6.022\times 10^{23}}\times 1=3.32\times 10^{-27}kg$

To calculate the wavelength of a particle, we use the equation given by De-Broglie's wavelength, which is:

$\lambda=\frac{h}{\sqrt{2mE_k}}$

where,

$\lambda$ = De-Broglie's wavelength = ?

h = Planck's constant = $6.624\times 10^{-34}Js$

m = mass of 1 hydrogen molecule = $3.32\times 10^{-27}kg$

$E_k$ = kinetic energy of the particle = $6.21\times 10^{-22}J$

Putting values in above equation, we get:

$\lambda=\frac{6.624\times 10^{-34}Js}{\sqrt{2\times 3.32\times 10^{-27}kg\times 6.21\times 10^{-22}J}}$

$\lambda=3.26\times 10^{-10}m=3.26\AA$ (Conversion factor: $1\AA=10^{-10}m$ )

Hence, the de-Broglie's wavelength of a hydrogen molecule is $3.26\AA$

3 0

3 years ago

calculate how many milliliters of 0.142 M NaOH are needed to completely neutralize 21.4 mL of 0.294 M H2C4H4O6.

Flura [38]

Answer:

The answer to your question is 88.7 ml

Explanation:

Data

Volume = ?

Concentration of NaOH = 0.142 M

Volume of H₂C₄H₄O₆ = 21.4 ml

Concentration of H₂C₄H₄O₆ = 0.294 M

Balanced chemical reaction

2 NaOH + H₂C₄H₄O₆ ⇒ Na₂C₄H₄O₆ + 2H₂O

1.- Calculate the moles of H₂C₄H₄O₆

Molarity = moles/volume

Solve for moles

moles = Molarity x volume

Substitution

moles = 0.294 x 21.4/1000

Result

moles = 0.0063

2.- Use proportions to calculate the moles of NaOH

2 moles of NaOH ------------------ 1 moles of H₂C₄H₄O₆

x ------------------ 0.0063 moles

x = (0.0063 x 2) / 1

x = 0.0126 moles of NaOH

3.- Calculate the volume of NaOH

Molarity = moles / volume

Solve for volume

Volume = moles/Molarity

Substitution

Volume = 0.0126/0.142

Result

Volume = 0.088 L or 88.7 ml

3 0

3 years ago

(pls help)

WITCHER [35]

Anthony’s because it explains way more

8 0

2 years ago

How many atoms are in 1.00 mol of calcium

SVEN [57.7K]

Answer: 6.02214076 atoms Ca

Explanation:

Ca is monoatomic, so atoms in 1 mol = avogadro number

6 0

2 years ago