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3 years ago

Given the following table, which statement is true about atoms A and B?

Chemistry

1 answer:

lisabon 2012 [21]3 years ago

6 0

Answer:

The statement true is A. A and B are isotopes of the same element.

Explanation:

Isotopes correspond to atoms of the same element with different mass numbers (A), that is to say they differ in the amount of neutrons in the nucleus. In the case of compound A it has 10 neutrons, and B has 11.

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Gold is alloyed (mixed) with other metals to increase its hardness in making jewelry.

KiRa [710]

Answer:

A) 54.04%

B) 13-karat

Explanation:

A) From the problem we have

1) Mg + Ms = 9.40 g

2) Vg + Vs = 0.675 cm³

Where M stands for mass, V stands for volume, and g and s stand for gold and silver respectively.

We can rewrite the first equation using the density values:

3) Vg * 19.3 g/cm³ + Vs * 10.5 g/cm³ = 9.40

So now we have a system of two equations (2 and 3) with two unknowns:

We express Vg in terms of Vs:

Vg + Vs = 0.675 cm³

Vg = 0.675 - Vs

We replace the value of Vg in equation 3:

Vg * 19.3 + Vs * 10.5 = 9.40

(0.675-Vs) * 19.3 + Vs * 10.5 = 9.40

13.0275 - 19.3Vs + 10.5Vs = 9.40

-8.8 Vs + 13.0275 = 9.40

Vs = 0.412 cm³

Now we calculate Vg:

Vg + Vs = 0.675 cm³

Vg + 0.412 cm³ = 0.675 cm³

Vg = 0.263 cm³

We calculate Mg from Vg:

0.263 cm³ * 19.3 g/cm³ = 5.08 g

We calculate the mass percentage of gold:

5.08 / 9.40 * 100% = 54.04%

We multiply 24 by the percentage fraction:

24 * 54.04/100 = 12.97-karat ≅ 13-karat

4 0

3 years ago

A student needs to prepare 100. mL of 0.612 M Cu(NO3)2 solution. What mass, in grams, of copper(II) nitrate should the student u

Temka [501]

Answer: 11.5 grams

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution

$Molarity=\frac{n\times 1000}{V_s}$

where,

Morality = 0.612 M

n= moles of solute

$V_s$ = volume of solution in ml = 100 ml

Now put all the given values in the formula of molarity, we get

$0.612=\frac{n\times 1000}{100ml}$

$n=0.0612moles$

$Mass={\text {moles of solute }}{\times {\text {molar mass}}=0.0612moles\times 187.56g/mol=11.5g$

Therefore, the mass of copper (II)nitrate required is 11.5 grams

3 0

3 years ago

What is the value of the equilibrium constant at 25 oC for the reaction between the pair: I2(s) and Br-(aq) Give your answer usi

insens350 [35]

Explanation:

Formula to calculate standard electrode potential is as follows.

$E^{o}_{cell} = E^{0}_{cathode} - E^{0}_{anode}$

= 0.535 - 1.065

= - 0.53 V

Also, it is known that relation between $E^{o}_{cell}$ and K is as follows.

$E^{o}_{cell} = \frac{RT}{nF} \times ln K$

ln K = $\frac{nFE^{0}_{cell}}{RT}$

Substituting the given values into the above formula as follows.

ln K = $\frac{nFE^{0}_{cell}}{RT}$

= $\frac{2 \times 96485 C mol^{-1} \times -0.53 V}{8.314 l atm/mol K \times 298 K} \times \frac{1 J}{1 V C}$

ln K = -41.28

K = $e^{-41.28}$

= $1 \times 10^{-18}$

Thus, we can conclude that the value of the equilibrium constant for the given reaction is $1 \times 10^{-18}$ .

5 0

3 years ago

A 453 g piece of glass at 25.7∘C is left outside on a sunny day. How much heat must the glass absorb from the sun in order to re

Tju [1.3M]

Answer:

Q = 5555.6J

Explanation:

Mass of glass piece, m = 453g

initial temperature = 25.7°C

temperature to be attained = 40.3°C

⇒change in temperature, Δt = 40.3 - 25.7 = 14.6°C

specific heat of glass, s = 0.840J/g°C

Heat absorbed, Q = msΔt

⇒Q = 453×0.840×14.6 = 5555.592J

⇒Q = 5555.6J (rounded to the nearest tenth)

7 0

3 years ago

When the temperature of an object changes by 10 °C the same temperature change in Kelvins would be

kumpel [21]

The answer to this question would be: 10 °K

Kelvin and Celcius scales are different by 273 degrees but their ratio is the same. One degree in Kelvin is equal to one degree in Celcius. That mean, 10 °C change in Celcius would be same as 10 °K changes in Kelvin too.

8 0

3 years ago