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3 years ago

An atom of Fe has 30 neutrons. What is the mass number of this atom?

Chemistry

1 answer:

SVETLANKA909090 [29]3 years ago

7 0

Answer:

Explanation:

The mass number of an atom is a sum of its number of protons and neutrons. Iron (Fe) has an atomic number of 26. This means that it has 26 protons. Since we know it has 26 protons and are told it has 30 neutrons. The mass number of this atom of Iron is 26+30 = 56

Hope this helped!

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Which of the following changes to a pipe would increase the conductance by a factor of 12?

ivanzaharov [21]

C. Tripling the length and reducing the radius by a factor of 2 is the change to a pipe would increase the conductance by a factor of 12.

Explanation:

As we know that the resistance is directly proportional to the length of the pipe and it is inversely proportional to the cross sectional area of the pipe.

So it is represented as,

R∝ l /A [ area is radius square]

So k is the proportionality constant used.

R = kl/A

Conductance is the inverse of resistance, so it is given as,

C= 1/R.

R₁ = kl₁ / A₁

R₂ = kl₂/A₂

R₂/R₁ = 1/12 [∵ conductance is the inverse of resistance]

= l₂A₁ / l₁A₂

If we chose l₁/l₂= 3 and A₂/A₁= 4 So R₂/R₁= 1/3×4 = 1/12

So tripling the length and reducing the radius by a factor of 2 would increase the conductance by a factor of 12.

6 0

3 years ago

Consider the following system at equilibrium where \Delta H° = 18.8 kJ, and Kc = 9.52×10-2, at 350 K.

slega [8]

Answer:

1. C. remains the same. 2. C. is less than Kc. 3. B. run in the reverse direction to reestablish equilibrium. 4. A. increase.

Explanation:

At constant temperature, the equilibrium concentration has not effect on the equilibrium constant because the rate constants do not change with change in the concentrations or amounts of the reactants or products. Change in the concentration of one reactant or product causes the concentration of the others to change so as to maintain a constant value for the equilibrium constant. On the other hand, the reaction quotient is used to measure the relative amounts of reactants and products during a chemical reaction at any point in time. The value of the reaction quotient shows the direction of the chemical reaction.

Therefore, when 0.31 moles of CCl4(g) are removed from the equilibrium system at constant temperature:

1. the value of Kc remains the same

2. the value of Qc is less than Kc

3. the reaction must run in the reverse direction to reestablish equilibrium

4. the concentration of $CH_{4}$ will increase because product will be converted to reactants to reestablish equilibrium.

7 0

3 years ago

What is the mass, in grams, of 1.33 mol of water, H2O?

Len [333]

Answer:

24.0g H2O

Explanation:

1.33 mol (18.016g/1 mol) = 24.0g H2O

8 0

3 years ago

The substances below are listed by increasing specific heat capacity value. Starting at 30 Celsius, they absorb 100 kJ of therma

Georgia [21]

Answer:

Silver.

Explanation:

To obtain the right answer to question, let us calculate the change in temperature for each substance assuming they all have the same mass as 100g.

This is illustrated below:

1. For Siver:

Mass (M) = 100g

Specific heat capacity (C) = 0.239J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 0.239)

ΔT = 4184°C

2. For Aluminium:

Mass (M) = 100g

Specific heat capacity (C) = 0.921J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 0.921)

ΔT = 1086°C

3. For Lithium:

Mass (M) = 100g

Specific heat capacity (C) = 3.56J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 3.56 )

ΔT = 281°C

4. For water:

Mass (M) = 100g

Specific heat capacity (C) = 4.184J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 4.184)

ΔT = 239°C

Summary

Temperature change of each substance is given below

1. Silver => 4184°C

2. Aluminum => 1086°C

3. Lithium => 281°C

4. Water => 239°C

From the calculations made above, Silver has the highest rise in temperature.

4 0

3 years ago

What is the ph of a solution that is 0.50 m in propanoic acid and 0.40 m in sodium propanoate. (ka for propanoic acid = 1.3 x 10

max2010maxim [7]

The pH is given by the Henderson - Hasselbalch equation:
 pH = pKa + log([A-]/[HA])
 pH = -log(1.3 x 10^-5) + log(0.50/0.40)
 pH = 4.98
The answer to this question is 4.98.

3 0

3 years ago