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3 years ago

Which of the following is an incorrect statement?

Chemistry

1 answer:

raketka [301]3 years ago

6 0

Sound is a form of energy is incorrect

Sound is caused by the movement or vibration of matter

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in 1912, chemist fritz haber developed a process that combined nitrogen from the air with hydrogen at high temperatures and pres

Virty [35]

Explain whether this is a chemical or physical change, and why. does it involve elements, compounds, mixtures, or pure substances?

If the process involves a chemical reaction then surely it is a chemical change where new bonds are being formed from the collision of the reactants.

Describe how many atoms are involved before and after. what do you notice about the number of atoms?

From the balanced chemical reaction, we see that we need 1 mol of N2 gas and 3 mol of H2 in order to form 2 mol of NH3.

3 0

2 years ago

What is the mass of 4.75 mol H2SO4

Over [174]

M(H2SO4)=n*M=4.75*98=465.5g

7 0

3 years ago

A microwave operates at 7.42 mm wavelength. How much energy is produced in Joules from 359 photons?

alisha [4.7K]

Answer:

$E=9.62\times 10^{-21}\ J$

Explanation:

Given that,

The wavelength of a microwave is 7.42 mm or 0.00742 m

No. of photons, n = 359

We need to find the energy produced by this no of photons. It can be given by the formula as follows :

$E=\dfrac{nhc}{\lambda}\\\\E=\dfrac{359\times 6.63\times 10^{-34}\times 3\times 10^8}{0.00742}\\\\=9.62\times 10^{-21}\ J$

$E=9.62e^{-21}\ J$

So, the required energy is $9.62\times 10^{-21}\ J$ .

3 0

3 years ago

Read 2 more answers

An ideal gas sealed in a rigid 4.86-L cylinder, initially at pressure Pi=10.90 atm, is cooled until the pressure in the cylinder

seraphim [82]

Answer:

$\Delta H=-11897J$

Explanation:

Hello,

In this case, it is widely known that for isochoric processes, the change in the enthalpy is computed by:

$\Delta H=\Delta U+V\Delta P$

Whereas the change in the internal energy is computed by:

$\Delta U=nCv\Delta T$

So we compute the initial and final temperatures for one mole of the ideal gas:

$T_1= \frac{P_1V}{nR}=\frac{10.90atm*4.86L}{0.082*n}=\frac{646.02K }{n} \\\\T_2= \frac{P_2V}{nR}=\frac{1.24atm*4.86L}{0.082*n}=\frac{73.49K }{n}$

Next, the change in the internal energy, since the volume-constant specific heat could be assumed as ³/₂R:

$\Delta U=1mol*\frac{3}{2} (8.314\frac{J}{mol*K} )*(73.49K-646.02K )=-7140J$

Then, the volume-pressure product in Joules:

$V\Delta P=4.86L*\frac{1m^3}{1000L} *(1.24atm-10.90atm)*\frac{101325Pa}{1atm} \\\\V\Delta P=-4756.96J$

Finally, the change in the enthalpy for the process:

$\Delta H=-7140J-4757J\\\\\Delta H=-11897J$

Best regards.

7 0

3 years ago

Calculate the concentration of A bottle of wine contains 12.9% ethanol by volume. The density of ethanol (CH3OH) is 0.789 g/cm e

Delicious77 [7]

Answer:

The mass percentage of the solution is 10.46%.

The molality of the solution is 2.5403 mol/kg.

Explanation:

A bottle of wine contains 12.9% ethanol by volume.

This means that in 100 mL of solution 12.9 L of alcohol is present.

Volume of alcohol = v = 12.9 L

Mass of the ethanol = m

Density of the ethanol ,d= $0.789 g/cm^3=0.789 g/mL$

$1 cm^3=1 mL$

$m=d\times v=0.798 g/ml\times 12.9 mL = 10.1781 g$

Mass of water = M

Volume of water ,V= 100 mL - 12.9 mL = 87.1 mL

Density of water = D=1.00 g/mL

$M=D\times V=1.00 g/ml\times 87.1 mL =87.1 g$

Mass percent

$(w/w)\%=\frac{m}{m+M}\times 100$

$\frac{10.1781 g}{10.1781 g+87.1 g}\times 100=10.46\%$

Molality :

$m=\frac{m}{\text{molar mass of ethanol}\times M(kg)}$

M = 87.1 g = 0.0871 kg (1 kg =1000 g)

$=\frac{10.1781 g}{46 g/mol\times 0.0871 kg}$

$m=2.5403 mol/kg$

4 0

3 years ago