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1 year ago

What is the energy change when 78.0 g of Hg melt at −38.8°C

Chemistry

1 answer:

adell [148]1 year ago

5 0

Answer:

The correct answer is - 2.557 KJ

Explanation:

In this case, Hg is melting, the process is endothermic, so the energy change will have a positive sign.

we can calculate this energy by the following formula:

Q = met

where, m = mass,

e = specific heat

t = temperature

then,

Q = 78*0.14* (273-38.8)

here 0.14 = C(Hg)

= 2.557 Kj

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In the nuclear transmutation, 168O (?, α)137N, what is the bombarding particle? In the nuclear transmutation, O (?, )N, what is

xeze [42]

Answer:

The bombarding particle is a Proton

Explanation:

A Nuclear transmutation reaction occurs when radioactive element decay, usually converting them from one element/isotope into another element. Transmutation is the process which causes decay, generally, alpha or beta.

¹⁶₈O(P,alpha) ¹³₇N, can be written as

¹⁶₈O + x goes to ¹³₇N + ⁴₂He

Where x can be anything, balancing the equation in order to give us the correct amount of proton number and nucleus number

16 + x = 13 + 4

x = 17 – 16 = 1, Hence we can say that x = ¹₁P

Here we can clearly see the bombarding particle is ¹₁P (proton). The ejected particle being ⁴₂He which is also known as an alpha particle

5 0

2 years ago

After careful analysis, an electromagnetic wave is found to have a frequency of 7.8 x 10^6 Hz. What is the speed of the wave?

damaskus [11]

Answer:

Explanation:

4 0

2 years ago

Analysis of a sample of a gaseous compound shows that it contains 85.7% C and 14.3% H by mass. At standard conditions, 112 mL of

KIM [24]

Answer: The molecular formula for the given compound is $C_3H_6$

Explanation : Given,

Percentage of C = 85.7 %

Percentage of H = 14.3 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 85.7 g

Mass of H = 14.3 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{85.7g}{12g/mole}=7.14moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{14.3g}{1g/mole}=14.3moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.14 moles.

For Carbon = $\frac{7.14}{7.14}=1$

For Hydrogen = $\frac{14.3}{7.14}=2.00\approx 2$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H = 1 : 2

The empirical formula for the given compound is $C_1H_2=CH_2$

Mass of empirical formula = $CH_2$ = 1(12) + 2(1) = 14 g/eq.

Now we have to determine the molar mass of compound.

As, 112 mL of volume contains 0.21 g of compound

So, 22400 mL of volume contains $\frac{22400}{112}\times 0.21=42g$ of compound

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is :

$n=\frac{\text{molecular mass}}{\text{empirical mass}}$

We are given:

Mass of molecular formula = 42 g/mol

Mass of empirical formula = 14 g/mol

Putting values in above equation, we get:

$n=\frac{42}{14}=3$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$CH_2=(CH_2)_n=(CH_2)_3=C_3H_6$

Thus, the molecular formula for the given compound is $C_3H_6$

4 0

2 years ago

Aliyah found a tarnished silver dollar and recalled that tarnish results when metals react with oxygen or sulfur compounds in th

snow_lady [41]

Answer:

Explanation:

Luster

5 0

2 years ago

What is the concentration of kl solution if 20.68g of solute was added to enough water to form 100ml solution?

rewona [7]

Answer:

1.25 M

Explanation:

Step 1: Given data

Mass of KI (solute): 20.68 g

Volume of the solution: 100 mL (0.100 L)

Step 2: Calculate the moles of solute

The molar mass of KI is 166.00 g/mol.

20.68 g × 1 mol/166.00 g = 0.1246 mol

Step 3: Calculate the molar concentration of KI

Molarity is equal to the moles of solute divided by the liters of solution.

M = 0.1246 mol/0.100 L= 1.25 M

5 0

2 years ago