Name two metalloids that are semiconductors

“When an animal looks a lot like another animal, even though they’re not the same kind of creature at all, it’s called

WITCHER [35]

Answer:

cryptic biodiversity

Explanation:

8 0

2 years ago

When 229.0 J of energy is supplied as heat to 3.00 mol of Ar(g) at constant pressure the temperature of the sample increases by

bazaltina [42]

Answer:

The molar heat capacity at constant volume is 21.62 JK⁻¹mol⁻¹

The molar heat capacity at constant pressure is 29.93 JK⁻¹mol⁻¹

Explanation:

We can calculate the molar heat capacity at constant pressure from

$C_{p,m} = \frac{C_{p} }{n}$

Where $C_{p,m}$ is the molar heat capacity at constant pressure

${C_{p} }$ is the heat capacity at constant pressure

and $n$ is the number of moles

Also ${C_{p} }$ is given by

${C_{p} } = \frac{\Delta H}{\Delta T}$

Hence,

$C_{p,m} = \frac{C_{p} }{n}$ becomes

$C_{p,m} = \frac{\Delta H }{n \Delta T}$

From the question,

$\Delta H$ = 229.0 J

$n$ = 3.00 mol

$\Delta T$ = 2.55 K

Hence,

$C_{p,m} = \frac{\Delta H }{n \Delta T}$ becomes

$C_{p,m} = \frac{229.0}{(3.00) (2.55)}$

$C_{p,m} =$ 29.93 JK⁻¹mol⁻¹

This is the molar heat capacity at constant pressure

For, the molar heat capacity at constant volume,

From the formula

$C_{p,m} = C_{v,m} + R$

Where $C_{v,m}$ is the molar heat capacity at constant volume

and $R$ is the gas constant ( $R$ = 8.314 JK⁻¹mol⁻¹)

Then,

$C_{v,m} = C_{p,m} - R$

$C_{v,m} = 29.93 - 8.314$

$C_{v,m} =$ 21.62 JK⁻¹mol⁻¹

This is the molar heat capacity at constant volume

5 0

3 years ago

What is the number of formula units in a 9.87 mol sample of NH4NO3 ?

Varvara68 [4.7K]

Answer:

59.42 ×10²³ formula units

Explanation:

Given data:

Number of moles of NH4NO3 = 9.87 mol

Number of formula units = ?

Formula:

Number of formula units = moles × Avogadro number

Solution:

Avogadro number = 6.02×10²³

Number of formula units = 9.87 × 6.02 ×10²³

Number of formula units = 59.42 ×10²³ formula units

5 0

3 years ago

What are some biological processes that are sensitive to pH changes?

Kipish [7]

Some processes including enzymes. Such as enzymes working in the stomach acid prefer a pH level of 2. If higher the enzymes don't work as efficiently.

6 0

3 years ago

A long (i.e., L >> D) stainless steel rod 6.4 mm in diameter is initially at a uniform temperature of 25°C and is suddenly

sp2606 [1]

Answer:

68.4 seconds

Explanation:

Assume that the temperature of the stainless steel rod will reach 120 C in t seconds. According to lumped – capacity analysis use the following expression to determine the value of t

T- T∞/T₀ – T∞ = e^-(hA/ρcV)t, where T is the required temperature, T∞ is the surface temperature, T₀ is initial temperature of the rod, h is the convection heat transfer coefficient, A is surface are, ρ is density of stainless steel, c is specific head and V is the volume of the rod.

Area of rod = π x d x L and Volume of rod is (π/4) x d² L

T - T∞/T₀ – T∞ = e^-(h x π x d x L/ρc(π/4 x d² x L))t

T - T∞/T₀ – T∞ = e^-(4h/(ρ x c x d))t, d is the radius of the log and L is the length of rod

The value of c and ρ for stainless steel can be obtained from the table of properties of metals

Substitute 120 C for T, 150 C for T∞, 25 C for T₀, 7817 kg/m³ for ρ, 460 J/kg.C for c, 6.4 x 10⁻³ m for d, 120 W/m².C for h in the above equation

T - T∞/T₀ – T∞ = e^-(4h/ρ x c x d))t

120 – 150/25 – 150 = e ^ -(4 x 120/7817 x 460 x 6.4 x 10⁻³)t

0.24 = e^-0.02086t

Take natural log on both sides

㏑0.24 = -0.02086t

T = 68.4 seconds

Thus, the temperature of the stainless steel will reach 120 C in 68.4s

5 0

3 years ago