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vfiekz [6]
3 years ago
8

If a sample of pure calcium (Ca) contains 4.69 x 1022 atoms of iodine, how many moles of calcium are in the sample?. A) 0.0779 m

ol. . B) 0.130 mol. C) 7.78 mol. D) 12.8 mol
Chemistry
1 answer:
timama [110]3 years ago
5 0
If a sample of pure calcium 9Ca) contains 4.69 x 1022 atoms of iodine, there are 0.0779 moles of calcium in the sample. The correct answer will be A. 
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15.3 g of nano3 were dissolved in 100g of water in a calorimeter. The temperature of the water drops from 25.00°c to 21.56°c. Ca
Arturiano [62]

Answer:

0.259 kJ/mol ≅ 0.26 kJ/mol.

Explanation:

  • To solve this problem, we can use the relation:

<em>Q = m.c.ΔT,</em>

where, Q is the amount of heat absorbed by ice (Q = ??? J).

m is the mass of the ice (m = 100.0 g).

c is the specific heat of water (c of ice = 4.186 J/g.°C).

ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = 21.56°C - 25.0°C = -3.44°C).

<em>∵ Q = m.c.ΔT</em>

∴ Q = (100.0 g)(4.186 J/g.°C)(-3.44°C) = -1440 J = -1.44 kJ.

<em>∵ ΔH = Q/n</em>

n = mass/molar mass = (100.0 g)/(18.0 g/mol) = 5.556 mol.

∴ ΔH = (-1.44 kJ)/(5.556 mol) = 0.259 kJ/mol ≅ 0.26 kJ/mol.

3 0
4 years ago
Which of the following is not part of a flower pistil
mafiozo [28]

Answer:

update the answer with the questions

Explanation:

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7 0
2 years ago
Identify each statement below as an example of science or pseudoscience.
kolezko [41]

Answer: pseudoscience

Explanation:

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3 0
3 years ago
Question 3<br> What part of a water molecule is the negatively charged side?
aleksandr82 [10.1K]

Answer:

The oxygen atom in water has a negative charge.

<h2>Definitions:</h2>

Polar molecule: A molecule in which the centroid of the positive charges is different from the centroid of the negative charges.

Oxygen: A colorless, odorless, gaseous element constituting about one-fifth of the volume of the atmosphere and present in a combined state in nature. It is the supporter of combustion in air and was the standard of atomic, combining, and molecular weights until 1961, when carbon 12 became the new standard. Symbol: O; atomic weight: 15.9994; atomic number: 8; density: 1.4290 g/l at 0°C and 760mm pressure.

Water: A transparent, odorless, tasteless liquid, a compound of hydrogen and oxygen, H2O, freezing at 32°F or 0°C and boiling at 212°F or 100°C. that in more or less impure state constitutes rain, oceans, lakes, rivers, etc.: it contains 11.188 percent hydrogen and 88.812 percent oxygen, by weight.

Hydrogen: A colorless, odorless, flammable gas that combines chemically with oxygen to form water: the lightest of the known element. Symbol: H; atomic weight: 1.00797; atomic number: 1; density: 0.0899 g/l at 0°C and 760 mm pressure.

Atom: Am atom is the smallest constituent particle of a chemical element which has the properties of that element. They re comprised of at least an electron and a portion, as is the case for Hydrogen. Atoms of all other elements however, contain at least one neutron.

Proton: A positively charged elementary particle that is a fundamental constituent of all atomic nuclei. It is the lightest and most stable baryon, having a charge equal in magnitude to that of the electron, a spin of 1/2, and a mass of 1.673 × 10-27kg. Symbol: P.

Electron: An elementary particle that is a fundamental constituent of matter, having a negative charge of 1.602 × 10-19 coulombs, ha mass of 9.108 × 10-31 kilograms, and spin of 1/23, and existing independently or as the component outside the nucleus of an atom.

Neutron: An elementary particle having no charge, mass slightly greater than that of a proton, and spin of 1/2: a constituent of the nuclei of all atoms except those of hydrogen. Symbol: n.

<h2>What is a negative charge?</h2>

A object has a negative charge when it consists of more electrons than protons.

With a partial positive charge on 2 Hs and a partial negative charge on oxygen, water molecules are polar molecules.

Actually, two hydrogen atoms and the core oxygen atom of water are covalently connected. Due to its greater electronegative nature than hydrogen, oxygen pulls the bound electron pair in the middle of the atom toward it.

When illustrating higher electron densities over oxygen, partial negative charge is used, whereas partial positive charge is used to illustrate lower densities over hydrogen atoms.

#SPJ2

3 0
2 years ago
The equilibrium constant is given for two of the reactions below. Determine the value of the missing equilibrium constant. A(g)
wolverine [178]

Answer:

The correct answer is 8.10

Explanation:

Given:

A(g) + 2B(g) ↔ AB₂(g)   Kc = 59 ---- Eq. 1

A(g) + 3B(g) ↔ AB₃(g)   Kc = 478 ----- Eq. 2

We have to rearrange the chemical equations in order to obtain:

AB₂(g) + B(g) ↔ AB₃(g) Kc = ?

AB₂(g) is a reactant, so we have to use the reverse reaction of Eq. 1, in this case Kc= 1/59. Since AB₃(g) is a product, we use the forward reaction of Eq.2, and the constant is the same: Kc= 478.  The following is the sum of rearranged chemical equations, and the compounds in bold and italic are canceled:

 AB₂(g)       ↔   <em>A(g)</em> + <em>2B(g)</em>          Kc₁= 1/59

<em>A(g)</em> + <em>3B(g)</em> ↔   AB₃(g)                  Kc₂= 478

-----------------------------------------

AB₂(g) + B(g) ↔ AB₃(g)

If we add reactions at equilibrium, the equilibrium constants Kc are mutiplied as follows:

Kc = Kc₁ x Kc₂ = 1/59 x 478 = 478/59 = 8.10

The value of the missing equilibrium constant is 8.10.

6 0
3 years ago
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