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3 years ago

The value of h for the reaction below is -73 kj how many kj of heat are released

1 answer:

7 0

If the value of H is positive, it means you have to add that much heat to complete the reaction. If H is negative, it means that much heat is released during the chemical process. Because it is -73 kJ, 73 kJ of heat are released in the reaction.

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Write a chemical equation of Dr. Jeff’s demonstration using a battery to light steel wool on fire. The battery is used to allow

Elis [28]

Answer:

2Fe(s) + 3O2(g) --------> 2FeO3(s)

Explanation:

According to the question, a battery was used to light the steel wool by bringing the terminals very close together. When the battery came into contact with the steel wool, current was sent out through the thin wire. This caused the iron to heat up quite well.

Iron reacts with oxygen under these conditions as follows;

2Fe(s) + 3O2(g) --------> 2FeO3(s)

This is the chemical reaction that occurs when the steel wool is set on fire.

6 0

3 years ago

A prion is an infectious self-reproducing protein structure. true or false

Alexandra [31]

Answer:

True is the correct answer.

Explanation:

The statement that a prion is an infectious, self-reproducing protein structure is true.

prion is an infectious particle and they do not have genetic material.

Prion present in the brain region that results in deadly neurodegenerative illnesses in humans and animals.

Prions are the self-producing proteinaceous infectious capable of transferring infection in the absence of the nucleic acids.
prions enter in the brain by an infection and they emerge from the variation in the gene that encodes the protein and once the prions present in the brain multiply by causing the benign proteins to refold into an abnormal form.

8 0

3 years ago

Hello, everyone!

marusya05 [52]

Answer: 27.09 ppm and 0.003 %.

First, for air pollutants, ppm refers to parts of steam or gas per million parts of contaminated air, which can be expressed as cm³ / m³. Therefore, we must find the volume of CO that represents 35 mg of this gas at a temperature of -30 ° C and a pressure of 0.92 atm.

Note: we consider 35 mg since this is the acceptable hourly average concentration of CO per cubic meter m³ of contaminated air established in the "National Ambient Air Quality Objectives". The volume of these 35 mg of gas will change according to the atmospheric conditions in which they are.

So, according to the law of ideal gases,

PV = nRT

where P, V, n and T are the pressure, volume, moles and temperature of the gas in question while R is the constant gas (0.082057 atm L / mol K)

The moles of CO will be,

n = 35 mg x $\frac{1 g}{1000 mg}$ x $\frac{1 mol}{28.01 g}$

→ n = 0.00125 mol

We clear V from the equation and substitute P = 0.92 atm and

T = -30 ° C + 273.15 K = 243.15 K

V = $\frac{0.00125 mol x 0.082057 \frac{atm L}{mol K} x 243 K}{0.92 atm}$

→ V = 0.0271 L

As 1000 cm³ = 1 L then,

V = 0.0271 L x $\frac{1000 cm^{3} }{1 L}$ = 27.09 cm³

Then the acceptable concentration c of CO in ppm is,

c = 27 cm³ / m³ = 27 ppm

To express this concentration in percent by volume we must consider that 1 000 000 cm³ = 1 m³ to convert 27.09 cm³ in m³ and multiply the result by 100%:

c = 27.09 $\frac{cm^{3} }{m^{3} }$ x $\frac{1 m^{3} }{1 000 000 cm^{3} }$ x 100%

c = 0.003 %

So, the acceptable concentration of CO if the temperature is -30 °C and pressure is 0.92 atm in ppm and as a percent by volume is 27.09 ppm and 0.003 %.

5 0

3 years ago

202H8(9) + 7 O2(g) > 4CO2(g) + 6 H2O(9).

lilavasa [31]

since the concentration of Carbon Dioxide will increase, it would make Q > K, cause equilibrium to shift in the direction with less moles of gas to alleviate the extra pressure. In this case, the reaction will shift left because there are fewer moles of gas present.

4 0

3 years ago

6.02 kJ>mol. When a small ice cube at -10°C is put into a cup of water at room temperature, which of the following plays a gr

9966 [12]

Answer:

Heat transfer during melting of ice plays greater role in cooling of liquid water.

Explanation:

Temperature of ice = -10 °c

Temperature of water = 0 °c

When ice cube is dipped in to the water.the heat transfer

Q = m c ΔT

⇒ Q = 1 × 2.01 × 10

⇒ Q = 20.1 KJ

Heat transfer during melting of ice $Q_{melt}$ = latent heat of ice

Latent heat of ice = 334 KJ

⇒ $Q_{melt}$ = 334 KJ

Heat transfer during melting of ice is greater value than heat transfer during warming of ice from -10°C to 0°C.

Thus heat transfer during melting of ice plays greater role in cooling of liquid water.

8 0

3 years ago