Which is more acidic, 4-ethoxyphenol or 4-nitrophenol?

A 1.00 cm2 blackbody surface emits 201 watts of radiant power. What is the temperature of the surface? Give to the nearest whole

erastovalidia [21]

Explanation:

Formula for black body radiation is as follows.

$\frac{P}{A} = \sigma \times T^{4} J/m^{2}s$

where, P = power emitted

A = surface area of black body

$\sigma$ = Stephen's constant = $5.6703 \times 10^{-8} watt/m^{2}.K^{-4}$

As area is given as 1.0 $cm^{2}$ . Converting it into meters as follows.

$1.00 cm^{2} \times \frac{(10^{-2})^{2} m^{2}}{1 cm^{2}}$ (as 1 m = 100 cm)

= $1 \times 10^{-4} m^{2}$

It is given that P = 201 watts. Hence,

$\frac{201 watts}{1 \times 10^{-4} m^{2}}$ = $5.6703 \times 10^{-8} watt/m^{2}.K^{-4} \times T^{4}$

$T^{4}$ = $35.45 \times 10^{12}$

T = $(35.45 \times 10^{12})^{1/4}$

= 8862.5 K

Thus, we can conclude that the temperature of the surface is 8862.5 K.

7 0

3 years ago

Which of the following elements is most likely to form a covalent bond?

Alecsey [184]

Bromine, it's the only element that isn't a metal

7 0

3 years ago

Menthol, the substance we can smell in mentholated cough drops, is composed of c, h, and o. a 9.045×10−2 −mg sample of menthol i

Ket [755]

Answer:

Empirical Formula = C₁₀H₂₀O

Solution:

Data Given:

Mass of Menthol = 9.045 × 10⁻² mg = 9.045 × 10⁻⁵ g

Mass of CO₂ = 0.2546 mg = 0.0002546 g

Mass of H₂O = 0.1043 mg = 0.0001043 g

Step 1: Calculate %age of Elements as;

%C = (mass of CO₂ ÷ Mass of sample) × (12 ÷ 44) × 100

%C = (0.0002546 ÷ 9.045 × 10⁻⁵) × (12 ÷ 44) × 100

%C = (2.814) × (12 ÷ 44) × 100

%C = 2.814 × 0.2727 × 100

%C = 76.73 %

%H = (mass of H₂O ÷ Mass of sample) × (2.02 ÷ 18.02) × 100

%H = (0.0001043 ÷ 9.045 × 10⁻⁵) × (2.02 ÷ 18.02) × 100

%H = (1.153) × (2.02 ÷ 18.02) × 100

%H = 1.153 × 0.1120 × 100

%H = 12.91 %

%O = 100% - (%C + %H)

%O = 100% - (76.73% + 12.91%)

%O = 100% - 89.64%

%O = 10.36 %

Step 2: Calculate Moles of each Element;

Moles of C = %C ÷ At.Mass of C

Moles of C = 76.73 ÷ 12.01

Moles of C = 6.3888 mol

Moles of H = %H ÷ At.Mass of H

Moles of H = 12.91 ÷ 1.01

Moles of H = 12.7821 mol

Moles of O = %O ÷ At.Mass of O

Moles of O = 10.36 ÷ 16.0

Moles of O = 0.6475 mol

Step 3: Find out mole ratio and simplify it;

C H O

6.3888 12.7821 0.6475

6.3888/0.6475 12.7821/0.6475 0.6475/0.6475

9.86 19.74 1

≈ 10 ≈ 20 1

Result:

Empirical Formula = C₁₀H₂₀O₁

8 0

3 years ago

What mass of sodium chloride is needed to prepare 200 ml of a 0.1 M solution

Nikolay [14]

Answer:

C. 1.17 grams

Explanation:

The molarity is the no. of moles of solute in a 1.0 L of the solution.

M = (mass/molar mass)solute x (1000/ V)

M = 0.1 M, mass = ??? g, molar mass of NaCl = 58.44 g/mol, V = 200.0 mL.

∴ mass of NaCl = (M)(molar mass)(V)/1000 = (0.1 M)(58.44 g/mol)(200.0 mL)/1000 = 1.168 g ≅ 1.17 g.

5 0

3 years ago

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Which of the following is a chemical change?

FromTheMoon [43]

Answer:

Silver tarnishing as the silver metal reacts with sulphur is a chemical change.

Explanation:

Tarnishing is the process of chemical change occurring on the surface of objects leading to corrosion or other defects on the surface. The remaining options like dilution, eroding is a physical change where the concentration of salt and rock particles will be decreased, respectively.

Similarly for soil drying also the concentration of water will be decreased leading to a physical change from wetty or dry soil.

But the last option which indicates tarnishing of silver metal on reaction with sulphur is a chemical process as the surface of silver metal will be reacting to sulphur and leads to lose of electrons which leads to corrosion of the surface or tarnishing of silver.

4 0

3 years ago

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