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3 years ago

A sample of table sugar has a mass of 5.432g a) calculate the number of moles in the sample

Chemistry

1 answer:

Temka [501]3 years ago

3 0

The number of particles of atoms depends on the ratio of their composition in the compound

<h3>Further explanation</h3>

Given

5.432 g of table sugar

Required

moles of sample

moles of C, H and O

number of atoms

Solution

Table sugar : Sucrose : C₁₂H₂₂O₁₁

moles of sample :

= 5.432 : 342,3 g/mol

= 0.016

moles of C, H, and O :

C = 12 x 0.016 = 0.192

H = 22 x 0.016 = 0.352

O = 11 x 0.016 = 0.176

number of atoms :

C = 0.192 x 6.02 x 10²³ = 1.16 x 10²³

H = 0.352 x 6.02 x 10²³ = 2.12 x 10²³

O = 0.176 x 6.02 x 10²³ = 1.06 x 10²³

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What do we call compounds that will not dissolve in water

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Answer:

covalent compounds

Explanation:

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How much of a 0.250 M lithium hydroxide is required to neutralize 20.0 mL of 0.345M chlorous acid?

Bumek [7]

Answer:

27.6mL of LiOH 0.250M

Explanation:

The reaction of lithium hydroxide (LiOH) with chlorous acid (HClO₂) is:

LiOH + HClO₂ → LiClO₂ + H₂O

<em>That means, 1 mole of hydroxide reacts per mole of acid</em>

Moles of 20.0 mL = 0.0200L of 0.345M chlorous acid are:

0.0200L ₓ (0.345mol / L) = <em>6.90x10⁻³ moles of HClO₂</em>

To neutralize this acid, you need to add the same number of moles of LiOH, that is 6.90x10⁻³ moles. As the LiOH contains 0.250 moles / L:

6.90x10⁻³ moles ₓ (1L / 0.250mol) = 0.0276L of LiOH =

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3 years ago

7. What is the prefix value for 100X?

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Answer:

hecto-

Explanation:

The prefix value of 100 is hecto therefore 100X can be called hecto-x.

Such prefixes as this are expressed in the order of tens. Units generally exists scientifically in multiples and submultiples form using prefixes.

For the multiples:

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For 100.0 mL of a solution that is 0.040M CH3COOH and 0.010 M CH3COO, what would be the pH after adding 10.0 mL 50.0 mM HCl?

damaskus [11]

Answer:

The pH of the buffer is 3.90

Explanation:

The mixture of a weak acid CH3COOH and its conjugate base CH3COO produce a buffer that follows the equation:

pH = pKa + log [A-] / [HA]

<em>Where pH is the pH of the buffer, pKa is the pKa of acetic acid (4.75), and [A-] could be taken as the moles of the conjugate base and [HA] the moles of thw weak acid.</em>

<em />

To solve this question we need to find the moles of the CH3COOH and CH3COO- after the reaction with HCl:

CH3COO- + HCl → CH3COOH + Cl-

<em>The moles of CH3COO- are its initial moles - the moles of HCl added</em>

<em>And moles of CH3COOH are its initial moles + moles HCl added</em>

<em />

Moles CH3COO-:

Initial moles = 0.100L * (0.010mol / L) = 0.00100moles

Moles HCl = 0.010L * (0.050mol / L) = 0.000500 moles

Moles CH3COO- = 0.000500 moles

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Initial moles = 0.100L * (0.040mol / L) = 0.00400moles

Moles HCl = 0.010L * (0.050mol / L) = 0.000500 moles

Moles CH3COO- = 0.003500 moles

pH is:

pH = 4.75 + log [0.000500] / [0.00350]

<em />

<h3>The pH of the buffer is 3.90</h3>

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Answer:

Along period electronegativity and ionization energy increases.

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Explanation:

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As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. Thus the attraction of the atoms for valance electrons increases. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required, and electronegativity also increases.

Along group:

As we move from top to bottom in periodic table the atomic sizes increases.The electrons are added in next energy level in every next element. Thus the valance electrons farther away from the nucleus and hold of nucleus becomes weaker, because of weak nuclear attraction atomic radii increases and electronegativity and ionization energy decreases.

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