What is the name of Se2Cl7?

What are alveoli and what do they do?

zlopas [31]

Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream

6 0

3 years ago

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Pre-Lab Study Questions / 9

jok3333 [9.3K]

Answer:

See detailed answer with explanation below.

Explanation:

Valence electrons are electrons found on the outermost shell of an atom. They are the electrons in an atom that participate in chemical combination. Recall that the outermost shell of an atom is also referred to as its valence shell. Let us consider an example; if we look at the atom, sodium-11, its electronic configuration is 2,8,1. The last one electron is the valence electron of sodium which is found in its outermost or valence shell.

Positive ions are formed when electrons are lost from the valence shell of an atom. For instance, if the outermost electron in sodium is lost, we now form the sodium ion Na^+ which is a positive ion. Positive ions possess less number of electrons compared to their corresponding atoms.

Negative ions are formed when one or more electrons is added to the valence shell of an atom. A negative ion possesses more electrons than its corresponding atom. For example, chlorine(Cl) contains 17 electrons but the chloride ion (Cl^-) contains 18 electrons.

In molecular compounds, a bond is formed when two electrons are shared between the bonding atoms. Each bonding atom may contribute one of the shared electrons (ordinary covalent bond) or one of the bonding atoms may provide the both shared electrons (coordinate covalent bond). The shared pair may be located at an equidistant position to the nucleus of both atoms. Similarly, the electron may be drawn closer to the nucleus of one atom than the other (polar covalent bond) depending on the electro negativity of the two bonding atoms.

The electrons are shared in order to complete the octet of each atom by so doing, the both bonding atoms now obey the octet rule. For example, two chlorine atoms may come together to form a covalent bond in which each chlorine atom has an octet of electrons on its outermost shell.

4 0

3 years ago

Under standard-state conditions, which of the following half-reactions occurs at the cathode during the electrolysis of aqueous

Slav-nsk [51]

Answer:

The following reaction will occur at cathode:

$Ni^{+2}(aq)+2e--->Ni(s)$

Explanation:

The two half reaction during electrolysis of aqueous nickel sulfate will be

a) anode reaction :

Water will undergo oxidation and will evolve oxygen gas at anode as shown in the given reaction:

$2H_{2}O(l) ----> O_{2}(g) + 4H^{+}(aq) + 4e$

b) Cathode reaction: The reduction of Nickel ion will occur by gain of two electrons as shown in the given equation:

$Ni^{+2}(aq)+2e--->Ni(s)$

Thus the overall reaction will be:

$2H_{2}O(l) + 2Ni^{+2}----> O_{2}(g) + 4H^{+}(aq) + 2Ni(s)$

6 0

3 years ago

The atomic number of an element is the total number of which particles in the nucleus?

VARVARA [1.3K]

An atom of element has there subatomic particles namely, proton, electron and neutron. Here, for a neutral atom, number of proton is equal to number of electron (this is not in the case of ions), this is equal to atomic number of an atom. In an atom, nucleus contains protons and neutrons which is responsible for mass of the atom and electrons move around nucleus in fixed orbits. Thus, atomic mass of an atom is equal to sum of number of protons and neutrons.

Option (b): Proton is the particle in nucleus of an atom, whose total number is equal to atomic number of that atom.

(4) Option (b): Atoms of same element have same atomic number because mass number can be different for different isotopes of atom. Since, atomic number is equal to number of protons, thus, number of protons are same for all atoms of the same element.

(5) Option (d): Isotopes are defined as atoms of same element with same atomic number but different mass number. Thus, correct option is (d) mass numbers.

4 0

3 years ago

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I’ll give brainliest please help thanks.

oksano4ka [1.4K]

Answer:

See Explanation

Explanation:

The equation of the reaction is;

C7H16(g) + 11O2(g) ---->7CO2(g) + 8H2O(g)

1a) Number of moles in 228 g of H2O = 228 g/18 g/mol = 12.67 moles

From the reaction equation;

11 moles of O2 yields 8 moles of H2O

x moles of O2 yields 12.67 moles of H2O

x = 11 * 12.67/8

x = 17.4 moles of O2

Since 1 mole of O2 occupies 22.4 L

17.4 moles of O2 occupies 17.4 moles * 22.4 L/1 mole = 389.76 L

1b) Molar mass of C7H16 = 100 g/mol

Number of moles in 300 g of C7H16 = 300 g/100g/mol = 3 moles

1 mole of C7H16 yields 7 moles of CO2

3 moles of C7H16 yields 3 * 7/1 = 21 moles of CO2

If 1 mole of CO2 occupies 22.4 L

21 moles of CO2 occupies 21 moles * 22.4 L/1 mole = 470.4 L of CO2

2) Number of moles in 202 L of H2 is obtained by;

1 mole of H2 occupies 22.4 L

x moles of H2 occupies 202 L

x = 1 mole * 202 L/22.4 L = 9 moles of H2

From the reaction equation;

3 moles of H2 yields 2 moles of PH3

9 moles of H2 will yield 9 * 2/3 = 6 moles of PH3

Mass of 6 moles of PH3 = 6 moles of PH3 * 34 g/mol = 204 g of PH3

3 0

3 years ago