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3 years ago

What are isotopes.....

1 answer:

6 0

The atoms of a chemical element can exist in different types. These are called isotopes. They have the same number of protons (and electrons), but different numbers of neutrons. Different isotopes of the same element have different masses. Mass is the word for how much substance (or matter) something has.

Isotopes are atom families that have the same number of protons, but different numbers of neutrons

Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

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A piece of metal with a mass of 23.2 g at 120.1oC is placed in a styrofoam cup containing 35.0 g of water at 22.2oC. Once the sy

earnstyle [38]

Answer:

0.8797 J/g oC

Explanation:

use mcAT=mcaT

3 0

1 year ago

Chlorofluorocarbons such as CCl2F and CCI,F, have been linked to ozone depletion in Antarctica. In 1994, these gases were found

Ilya [14]

Answer:

a) molarity of CCl3F = 1.12 × 10^-11 mol/dm³

Molarity of CCl2F2 = 2.20 × 10^-11 mol/dm³

B) molarity of CCL3F = 7.96 × 10 ^-13 mol/dm³

Molarity of CCl2F2 = 1.55 × 10^-12 mol/dm³

Explanation:

Using the ideal gas equation:

PV = nRT

Further explanations are found in the attachment below.

4 0

3 years ago

What is the predominant intermolecular force in the liquid state of each of these compounds: hydrogen fluoride (HF), carbon tetr

telo118 [61]

Answer:

HF - hydrogen bonding

CBr4 - Dispersion

NF3 - Dipole-dipole

Explanation:

Hydrogen bonding occurs when hydrogen is covalently bonded to a highly electronegative atom such as fluorine, chlorine nitrogen, oxygen etc. Hence the dominant intermolecular force in HF is hydrogen bonding.

CBr4 is nonpolar because the molecule is tetrahedral and the individual C-Br dipole moments cancel out leaving the molecule with a zero dipole moment hence the dominant intermolecular force are the dispersion forces.

NF3 has a resultant dipole moment hence the molecules are held together by dipole-dipole interaction.

4 0

2 years ago

What was the oxygen crisis

salantis [7]

The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust,[2] or Oxygen Revolution, was a time period when the Earth's atmosphere and the shallow ocean first experienced a rise in oxygen, approximately 2.4 billion years ago (2.4 Ga) to 2.1–2.0 Ga during the Paleoproterozoic era.[3] Geological, isotopic, and chemical evidence suggests that biologically produced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere,[4] causing many existing species on Earth to die out.[5] The cyanobacteria producing the oxygen caused the event which enabled the subsequent development of multicellular forms.

8 0

3 years ago

A solution is made by dissolving

barxatty [35]

Answer:

4.52 mol/kg

Explanation:

Given data:

Mass of lithium fluoride = 22.1 g

Mass of water = 188 g

Molality = ?

Solution:

Molality:

It is the number of moles of solute into kilogram of solvent.

Formula:

Molality = number of moles of solute / kilogram solvent

Mathematical expression:

m = n/kg

Now we will convert the grams of LiF into moles.

Number of moles = mass/ molar mass

Number of moles = 22.1 g/ 26 g/mol

Number of moles = 0.85 mol

Now we will convert the g of water into kg.

Mass of water = 188 g× 1kg/1000 g = 0.188 kg

Now we will put the values in formula.

m = 0.85 mol / 0.188 kg

m = 4.52 mol/kg

8 0

3 years ago