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2 years ago

Why would it be more comfortable to walk on hot beach sand in flip-flops

Chemistry

1 answer:

Eddi Din [679]2 years ago

8 0

Answer:

D. Thermal conduction is blocked by the flip-flops.

Explanation:

Convection is a process of heat transfer which involves fluids( liquid or gas). This however rules convection out of the answer.

Radiation involves heat transfer from the sun to bodies on earth.

Conduction involves heat transfer between two solid bodies. Hot beach sand and flip-flops are solid bodies which validates thermal(heat) conduction.

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Ozone is dangerous to human health only when it is found in the what?

Irina18 [472]

Only when it is found in the atmosphere, because it will create a hole, letting strong UV rays shine down on earth, heating it up, and causing skin cancer in humans and other animals.

4 0

2 years ago

Read 2 more answers

The beginning of this chemical equation represents the

katovenus [111]

Answer:

C. H₂SO₄

Explanation:

Given expression:

H₂O + SO₃ → H₂SO₄

In the chemical reaction, the product and the reactant have the same species.

Chemical reactions obeys the law of conservation of matter.

This way, atoms combine with one another to give a desired product. The products will contain a mix of the reactants.

Fluorine is not part of the reactants
Carbon is not part of the reactants
Carbon is not part of the reactants.

5 0

2 years ago

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What is the equilibrium membrane potential due to na ions if the extracellular concentration of na ions is 142 mm and the intrac

Ganezh [65]

The equilibrium membrane potential is 41.9 mV.

To calculate the membrane potential, we use the Nernst Equation:

V_Na = (RT)/(zF) ln{[Na]_o/[Na]_ i}

where

• V_Na = the equilibrium membrane potential due to the sodium ions

• R = the universal gas constant [8.314 J·K^(-1)mol^(-1)]

• T = the Kelvin temperature

• z = the charge on the ion (+1)

• F = the Faraday constant [96 485 C·mol^(-1) = 96 485 J·V^(-1)mol^(-1)]

• [Na]_o = the concentration of Na^(+) outside the cell

• [Na]_i = the concentration of Na^(+) inside the cell

∴ V_Na =

[8.314 J·K^(-1)mol^(-1) × 293.15 K]/[1 × 96 485 J·V^(-1)mol^(-1)] ln(142 mM/27 mM) = 0.025 26 V × ln5.26 = 1.66× 25.26 mV = 41.9 mV

4 0

2 years ago

A 825 g iron block is heated to 352 degrees C and is placed in an insulated container (of negligible heat capacity) containing 4

Stella [2.4K]

Answer : The final equilibrium temperature of the water and iron is, 537.12 K

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

where,

$c_1$ = specific heat of iron = 560 J/(kg.K)

$c_1$ = specific heat of water = 4186 J/(kg.K)

$m_1$ = mass of iron = 825 g

$m_2$ = mass of water = 40 g

$T_f$ = final temperature of water and iron = ?

$T_1$ = initial temperature of iron = $352^oC=273+352=625K$

$T_2$ = initial temperature of water = $20^oC=273+20=293K$

Now put all the given values in the above formula, we get:

$(825\times 10^{-3}kg)\times 560J/(kg.K)\times (T_f-625K)=-(40\times 10^{-3}kg)\times 4186J/(kg.K)\times (T_f-293K)$

$T_f=537.12K$

Therefore, the final equilibrium temperature of the water and iron is, 537.12 K

8 0

2 years ago

Which solution below has the highest concentration of hydroxide ions?a. pH= 3.21b. pH= 7.00c. pH= 7.93d. pH= 12.59e. pH= 9.82

Sloan [31]

Answer:

The solution that has the highest concentration of hydroxide ions is d. pH = 12.59.

Explanation:

You can solve this question using just some chemical facts:

pH is a measure of acidity or alkalinity: the higher the pH the lower the acidity and the higher the alkalinity.
The higher the concentration of hydroxide ions the lower the acidity or the higher the alkalinity of the solution, this is the higher the pH.

Hence, since you are asked to state the solution with the highest concentration of hydroxide ions, you just pick the highest pH. This is the option d, pH = 12.59.

These mathematical relations are used to find the exact concentrations of hydroxide ions:

pH + pOH = 14 ⇒ pOH = 14 - pH

pOH = - log [OH⁻] ⇒ $[OH^-]=10^{-pOH}$

Then, you can follow these calculations:

Solution pH pOH [OH⁻]

a. 3.21 14 - 3.21 = 10.79 antilogarithm of 10.79 = 1.6 × 10⁻¹¹

b. 7.00 14 - 7.00 = 7.00 antilogarithm of 7.00 = 10⁻⁷

c. 7.93 14 - 7.93 = 6.07 antilogarithm of 6.07 = 8.5 × 10⁻⁷

d. 12.59 14 - 12.59 = 1.41 antilogarithm of 1.41 = 0.039

e. 9.82 14 - 9.82 = 4.18 antilogarithm of 4.18 = 6.6 × 10⁻⁵

From which you see that the highest concentration of hydroxide ions is for pH = 12.59.

5 0

2 years ago