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4 years ago

What gives the gem amethyst its purplish color?

1 answer:

5 0

The question is asking us to determine what gives the Amethyst its purplish color. Amethyst colors range from light to dark purple. The most highly regarded are the transparent deep purple colors. Amethyst ( chemical formula: Si O2 ) is the purple variety of the mineral Quartz.The pure Quartz is often colorless. Amethyst gets its purplish color because of the presence of Iron ( Fe ) and other impurities in the gem. Answer: C. Iron.

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An unknown gas diffuses 1.25 times faster than CO2 gas. What is the molar mass of the unknown gas?

hodyreva [135]

Answer:

28.16 g/mol

Explanation:

From Graham's law;

Let the rate of diffusion of gas X be 1.25

Let the rate of diffusion of CO2 be 1

Molecular mass of gas X= M

Molecular mass of CO2 = 44g/mol

1.25/1=√44/M

(1.25/1)^2 = 44/M

1.5625 = 44/M

M= 44/1.5625

M= 28.16 g/mol

4 0

3 years ago

[Co(H2O)6]2+(aq) + 4Cl-(aq) ⇌ [CoCl4]2-(aq) + 6H2O(l)

pav-90 [236]

Answer:

For A: The expression for $K_{eq}$ is given below.

For B: The value of $K_{eq}$ at 25°C is 0.0185512

For C: The value of $K_{eq}$ at 65°C is 0.2887886

For D: The reaction is endothermic in nature.

Explanation:

For A:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as $K_{eq}$

For the given chemical reaction:

$[Co(H_2O)_6]^{2+}(aq.)+4Cl^-(aq.)\rightleftharpoons [CoCl_4]^{2-}(aq.)+6H_2O(l)$

The expression of $K_{eq}$ for above equation without the concentration of liquid water is:

$K_{eq}=\frac{[CoCl_4]^{2-}}{[Co(H_2O)_6]^{2+}[Cl^-]^4}$ ......(1)

The expression is written above.

For B:

We are given:

$[CoCl_4]^{2-}=0.0334612M$

$[Co(H_2O)_6]^{2+}=0.966539M$

$[Cl^-]=1.86616M$

Putting values in equation 1, we get:

$K_{eq}=\frac{0.0334612}{0.966539\times 1.86616}=0.0185512$

Hence, the value of $K_{eq}$ at 25°C is 0.0185512

For C:

We are given:

$[CoCl_4]^{2-}=0.234625M$

$[Co(H_2O)_6]^{2+}=0.765375M$

$[Cl^-]=1.06150M$

Putting values in equation 1, we get:

$K_{eq}=\frac{0.234625}{0.765375\times 1.06150}=0.2887886$

Hence, the value of $K_{eq}$ at 65°C is 0.2887886

For D:

For Endothermic reactions, $\Delta H>0$ , which is positive

For Exothermic reactions, $\Delta H$ , which is negative

To calculate $\Delta H$ of the reaction, we use Van't Hoff's equation, which is:

$\ln(\frac{K_{65^oC}}{K_{25^oC}})=\frac{\Delta H}{R}[\frac{1}{T_1}-\frac{1}{T_2}]$

where,

$K_{65^oC}$ = equilibrium constant at 65°C = 0.2887886

$K_{25^oC}$ = equilibrium constant at 25°C = 0.0185512

$\Delta H$ = Enthalpy change of the reaction = ?

R = Gas constant = 8.314 J/mol K

$T_1$ = initial temperature = $25^oC=[25+2730]K=298K$

$T_2$ = final temperature = $65^oC=[65+2730]K=338K$

Putting values in above equation, we get:

$\ln(\frac{0.2887886}{0.0185512})=\frac{\Delta H}{8.314J/mol.K}[\frac{1}{298}-\frac{1}{338}]\\\\\Delta H=57471.26J/mol$

As, the calculated value of $\Delta H>0$ . Thus, the reaction is endothermic in nature.

4 0

4 years ago

What is the frequency of a wave traveling at 5,000 m/s with a wavelength of .002 m/cycle?

Korvikt [17]

Answer:

$2.5\cdot 10^6 Hz$

Explanation:

The relationship between the speed of a wave, its frequency and its wavelength is given by the wave equation:

$v=f\lambda$

where

v is the wave speed

f is the frequency of the wave, which is the number of cycles completed by the wave in one oscillation

$\lambda$ is the wavelength, which is the distance between two consecutive crests of the wave

For the wave in this problem we have:

v = 5000 m/s is the speed

$\lambda=0.002 m$ is the wavelength of the wave

Solving for f, we find the frequency:

$f=\frac{v}{\lambda}=\frac{5000}{0.002}=2.5\cdot 10^6 Hz$

8 0

3 years ago

Suppose that 273 of a substance displaces 26ml of water what is the substance

Llana [10]

273g/25 mL = 10.92 (that's the density)
What has a density of 10.92 grams/mL? I don't know but I bet it's in your notes or on the worksheet.

3 0

3 years ago

Patients with prostheses needing repair or replacement usually require surgery. However, one type of prosthesis needs no externa

zysi [14]

I believe the answer is a. A passive prosthesis

Prosthesis is used to replace a part of the patient. Some prosthesis powered by external source that allow it to do some degree of movement. Passive prosthesis doesn't have electronic or mechanic part, which makes their function is more to be cosmetic than function.

7 0

3 years ago

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