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3 years ago

What is chemistry? I NEED HELP ASAP!

1 answer:

3 0

the branch of science that deals with the identification of the substances of which matter is composed; the investigation of their properties and the ways in which they interact, combine, and change; and the use of these processes to form new substances.the branch of science that deals with the identification of the substances of which matter is composed; the investigation of their properties and the ways in which they interact, combine, and change; and the use of these processes to form new substances.

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Determine how many grams of N2 are produced from the reaction of 8.37 g of H2O2 and 5.29 g of N2H4.

Dmitriy789 [7]

N₂H₄ + 2H₂O₂    → N₂ + 4H₂O

mol = mass ÷ molar mass

If mass of hydrazine (N₂H₄) = 5.29 g
then mol of hydrazine = 5.29 g ÷ ((14 ×2) + (1 × 4))
  = 0.165 mol

mole ratio of hydrazine to Nitogen is 1 : 1
  ∴ if moles of hydrazine = 0.165 mol
then moles of nitrogen = 0.165 mol

Mass = mol × molar mass

Since mol of nitrogen (N₂) = 0.165
then mass of hydrazine    = 0.165 × (14 × 2)
   = 4.62 g

5 0

3 years ago

Compare molecular & covalent network crystal solid?

Daniel [21]

Answer:

Molecular solids and covalent network solids are two types of solid compounds. The key difference between molecular solid and covalent network solid is that molecular solid forms due to the action of Van der Waal forces where as covalent network solid forms due to the action of covalent chemical bonds.

hope this helps

8 0

1 year ago

which of the following substances is least able to cross the blood-brain barrier.)a. waterb. sodium ionsc glucosed. white blood

ivolga24 [154]

Answer:

d. white blood cells

Explanation:

It is the white blood cells that have the least tendency to cross the blood- brain barrier.

Blood- brain barrier is psychological barrier and restricts substances that circulate into the blood from crossing over the central nervous system.

Water, glucose as well as sodium ions can easily cross the barrier. As these are good for body supply energy to the brain.

8 0

3 years ago

Which of the following molecules would exhibit only London forces?a)CH4, BH3, and CCl4b)H2O, NH3, and CCl4c)PH3, NH3, and CCl4

Alex787 [66]

Answer:

a)CH₄, BH₃, and CCl₄

Explanation:

London dispersion forces:-

The bond for example, in the molecule is F-F, which is non-polar in nature because the two fluorine atoms have same electronegativity values.

The intermolecular force acting in the molecule are induced dipole-dipole forces or London Dispersion forces / van der Waals forces which are the weakest intermolecular force.

Out of the given options, H₂O , NH₃ exhibits hydrogen bonding which is:-

Hydrogen bonding:-

Hydrogen bonding is a special type of the dipole-dipole interaction and it occurs between hydrogen atom that is bonded to highly electronegative atom which is either fluorine, oxygen or nitrogen atom.

Thus option B and C rules out.

Hence, the correct option which represents the molecules which would exhibit only London forces is:- a)CH₄, BH₃, and CCl₄

4 0

3 years ago

1. Oxygen was discovered by Joseph Priestley in 1774 when he heated mercury (II) oxide, HgO, to decompose it to form its constit

Tomtit [17]

Answer:

1. 7.81 moles HgO

2. n = mass/molar mass = (4000 g)/(159.69 g/mol) = 25.05 mol.

Explanation:

How many moles of mercury (II) oxide are needed to produce 125 g of oxygen?

2HgO ==> 2Hg + O2

125 g O2 x 1 mol O2/32 g x 2 mol HgO / mol O2 = 7.81 moles HgO

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If 4000 g of Fe2O3 is available to react, how many moles of CO are needed?

The no. of moles of CO are needed = 75.15 mol.

Fe₂O₃ + 3CO → 2Fe + 3CO₂,

It is clear that 1 mol of Fe₂O₃ reacts with 3 mol of CO to produce 2 mol of Fe and 3 mol of CO₂.

If 4.00 kg Fe₂O₃ are available to react, how many moles of CO are needed?

We need to calculate the no. of moles of 4.00 kg Fe₂O₃:

n = mass/molar mass = (4000 g)/(159.69 g/mol) = 25.05 mol.

Using cross multiplication:

1 mol of Fe₂O₃ need → 3 mol of CO to react completely, from stichiometry.

25.05 mol of Fe₂O₃ need → ??? mol of CO to react completely.

The no. of moles of CO are needed = (3 mol)(25.05 mol)/(1 mol) = 75.15 mol.

6 0

2 years ago