Ask question

Ask question

All categories

3 years ago

7

Calculate the heat required to convert 10g of water at 100 c to steam at 100 c the specific heat of water is 1.00 cal the heat o

f fusion is 80 and the heat of vap is 540

1 answer:

sladkih [1.3K]3 years ago

3 0

Heat of vaporization of water will be required as water is already at it's boiling point thus heat required will be 540*10=5400 cal

You might be interested in

A mixture of helium, nitrogen and oxygen has a total pressure of 756 mmHg. The partial

Karolina [17]

Answer:

The partial pressure of oxygen in the mixture is 296 mmHg.

Explanation:

The pressure exerted by a particular gas in a mixture is known as its partial pressure. So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone.

This relationship is due to the assumption that there are no attractive forces between the gases.

So, in this case, the total pressure is:

PT=Phelium + Pnitrogen + Poxygen

You know:

PT= 756 mmHg
Phelium= 122 mmHg
Pnitrogen= 338 mmHg
Poxygen= ?

Replacing:

756 mmHg= 122 mmHg + 338 mmHg + Poxygen

Solving:

756 mmHg - 122 mmHg - 338 mmHg = Poxygen

Poxygen= 296 mmHg

<u><em>The partial pressure of oxygen in the mixture is 296 mmHg.</em></u>

6 0

3 years ago

How many molecules are in 7.62 L of CH4, at 87.5°C and 722 torr

pickupchik [31]

Answer: There are $1.469 \times 10^{23}$ molecules present in 7.62 L of $CH_4$ at $87.5^{o}C$ and 722 torr.

Explanation:

Given : Volume = 7.62 L

Temperature = $87.5^{o}C = (87.5 + 273) K = 360.5 K$

Pressure = 722 torr

1 torr = 0.00131579

Converting torr into atm as follows.

$722 torr = 722 torr \times \frac{0.00131579 atm}{1 torr}\\= 0.95 atm$

Therefore, using the ideal gas equation the number of moles are calculated as follows.

PV = nRT

where,

P = pressure

V = volume

n = number of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

$PV = nRT\\0.95 atm \times 7.62 L = n \times 0.0821 L atm/mol K \times 360.5 K\\n = \frac{0.95 atm \times 7.62 L}{0.0821 L atm/mol K \times 360.5 K}\\= \frac{7.239}{29.59705}\\= 0.244 mol$

According to the mole concept, 1 mole of every substance contains $6.022 \times 10^{23}$ atoms. Hence, number of atoms or molecules present in 0.244 mol are calculated as follows.

$0.244 mol \times 6.022 \times 10^{23}\\= 1.469 \times 10^{23}$

Thus, we can conclude that there are $1.469 \times 10^{23}$ molecules present in 7.62 L of $CH_4$ at $87.5^{o}C$ and 722 torr.

5 0

3 years ago

An ion with 5 protons, 6 neutrons, and a charge of 3+ has an atomic number of

user100 [1]

Answer:1. 5

Explanation: the element is boron and the atomic number is 5

6 0

3 years ago

Define the following and give an example of each:_______.

Ber [7]

<h2>Hey There!</h2><h2>_____________________________________</h2><h2>Answer:</h2><h2>_____________________________________</h2><h2> $\huge\textbf{Van de Waal}$ </h2>

London Dispersion force or Van de Waals force is a temporary attractive force which are the weakest and occur between nonpolar noble gases and same charges. This force is weaker because they have more electrons that are farther from the nucleus and are able to move around easier.

Example: $N_2$ , $F_2, \ I_2$

<h2>_____________________________________</h2>

$\huge\textbf{Dipole - Dipole Forces}$

Dipole force is present between the polar molecules. Polar molecules are those molecules which have slightly negative and slightly positive charge. Dipole-dipole forces are attractive forces between the positive end of one polar molecule and the negative end of another polar molecule.

Example: HCl, HF, $CHCl_3$

<h2>_____________________________________</h2>

$\huge\textbf{Hydrogen Bonding}$

It is a special type of dipole force present between polar molecules, it is formed between Hydrogen atom which forms positive ion, and the other negative ion. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom. The hydrogen bond is one of the strongest intermolecular attractions, but weaker than a covalent or an ionic bond.

Example: Every polar molecule which has hydrogen has hydrogen bonding i.e. $H_2O, NH_3$

<h2>_____________________________________</h2><h2>Best Regards,</h2><h2>'Borz'</h2><h2 />

6 0

3 years ago

1.A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. How much calcium is contained in 40.0 g of

QveST [7]

These are five questions and five answers.

1) <u>Question 1.</u> A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. How much calcium is contained in 40.0 g of calcium fluoride?

Answer:

<u><em>20.5 g Ca</em></u>

Explanation:

<em>Calcium fluoride</em> being a pure substance, has a fixed chemical compositon, which means that their elements (atoms), in any sample, are always in the same proportion.

Then, you can set the followoing proportion:

7.70 g Ca / 15.0 g CaF₂ = x / 40.0 g CaF₂

Now, solve for x:

x = 40.0 g CaF₂ × 7.70 g Ca / 15.0 g CaF₂ = 20.5 g Ca.

The answer must be expressed with 3 significan figures, since the three data are given with 3 significan figures.

2)<u> Question 2</u>. Silver has two isotopes. One isotope contains 60 neutrons and has a percent abundance of 51.839% the other contains 62 neutrons. Give the atomic symbols for the two isotopes.

Answer:

<em>Isotope that contains 60 neutrons: </em><u>¹⁰⁷₄₇Ag</u>

<em>Isotope that contains 62 neutrons: </em><u>¹⁰⁹₄₇Ag</u>

Explanation:

<em>Isotopes</em> are atoms of the same element, with different number of <em>neutrons,</em> so all the isotopes of an element have the same atomic number, Z (number of protons) and different mass number A (number of neutrons + protons).

The atomic symbols for isotopes uses the chemical symbol of the atom (Ag for silver); a subscript to the left of the chemical symbol that represents the atomic mass (47 for silver); and a superscript to the left of the chemical symbol that represents the mass number.

The mass number, A, for each silver isotope is calculated in this way:

Isotope that contains 60 neutrons: A = 60 + 47 = 107

Isotope that contains 62 neutrons: A = 62 + 47 = 109

Then, the respective atomic symboles are:

Isotope with 60 neutrons: ¹⁰⁷₄₇Ag

Isotope with 62 neutrons: ¹⁰⁹₄₇Ag

3) <u>Question 3.</u> What is the average atomic weight of silver? What is the mass (in grams) of a single chlorine molecule?

Answer:

<u><em>107.96 amu</em></u>

Explanation:

The atomic wieght of the elements is the weighted average weight of the different isotopes of the same element found in the nature, taking into account their relative abundance.

Average atomic weight = ∑( abundance × individual atomic weight)

Average atomic weight of silver = (abundace of isotope 1 × atomic weight isotope 1) + (abundance isotope 2 × atomic weight isotope 2)

Abundance isotope 1 = 51.839%

Atomic weight isotope 1 = mass number = 60 neutrons + 47 protons = 107 a.m.u
Abundance isotope 2 = 100% - 51.839% = 48.161%

Atomic weight isotope 2 = 62 neutrons + 47 protons = 109 a.m.u.

Average atomic weight of silve = 107 amu × 51.839% + 109 amu × 48.161% = 107.96 amu

4) <u>Question without number</u>: What is the mass (in grams) of a single chlorine molecule

Answer:

<u><em>1.177 × 10⁻²² g</em></u>

Explanation:

The chlorine molecule is diatomic. That means that each molecule contains two atoms. The chemical formula of chlorine molecule is Cl₂.

The mass of one mole of molecules of Cl₂ is 2 × 35.453 g/mol = 70.906 g/mol

Mass of a single molecule = mass of one mol / number of molecules in one mol

Mass of a single molecule = 70.906 g/mol / (6.022 × 10²³ molecules / mol)

Mass of a single molecule = 11.77 × 10⁻²³ g = 1.177 × 10⁻²² g

5) <u>Question 4. </u>How many moles of ethanol (CH₃CH₂OH) are in 141 mg?

Answer:

<u><em>0.00301 mol</em></u>

Explanation:

Molar mass of CH₃CH₂OH = 2 × 12.011 g/mol + 6 × 1.008 g/mol + 15.999 g/mol = 46.069 g/mol.

Formula: number of moles = mass in grams / molar mass

Calculation: number of moles = 141 mg × ( 1 g /1000 mg) / (46.069 g/mol = 0.00301 mol

4 0

3 years ago