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2 years ago

A given sample of caffeine, C8H10N4O2, has 6.47 x 1022

Chemistry

1 answer:

Verdich [7]2 years ago

3 0

Answer:

8.08 × $10^{22}$ atoms of hydrogen

Explanation:

From the given data, we have two categories of variables (unknowns):

Amount (moles or mass) of Caffeine
Amount (moles or mass) of Hydrogen

The longer route would be to solve for these variables first, by determining the number of moles of the Caffeine sample (0.134 moles of C8H10N4O2) from the mass of carbon (12.89 g = 1.07 moles in 6.47 $10^{22}$ atoms) provided. And then solve for the number of atoms of H. [N.B: 1 mole of ANY substance = 6.022 × $10^{22}$ atoms ]

Alternatively and quicker, we can use the mole ratios of the Carbon:Hydrogen atoms in the compound.

8 : 10 ≡ 4 : 5

If 4 moles -- 6.47 $10^{22}$ atoms

Then 5 moles -- ?? atoms

⇒ No. of atoms of Hydrogen = $\frac{5*6.47*10^{22}}{4}$

=8.08 × $10^{22}$ atoms of hydrogen

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A gem has a mass of 4.50 g. When the gem is placed in a graduated cylinder 12.00 mL of water, the water level rises to 13.45 mL.

Mandarinka [93]

Displaced volume :

Final volume - Initial volume

13.45 mL - 12.00 mL => 1.45 mL

Mass = 4.50 g

Therefore:

density = mass / volume

D = 4.50 / 1.45

D = 3.103 g/mL

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2 years ago

What is molarity of 3 mole of hydrochloric acid in 3L of water

Mila [183]

Answer:

Explanation:

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2 years ago

In Part A, you found the amount of product (1.80 mol P2O5 ) formed from the given amount of phosphorus and excess oxygen. In Par

Finger [1]

First step is to balance the reaction equation. Hence we get P4 + 5 O2 => 2 P2O5

Second, we calculate the amounts we start with

P4: 112 g = 112 g/ 124 g/mol – 0.903 mol

O2: 112 g = 112 g / 32 g/mol = 3.5 mol

Lastly, we calculate the amount of P2O5 produced.

2.5 mol of O2 will react with 0.7 mol of P2O5 to produce 1.4 mol of P2O5.

This is 1.4 * (31*2 + 16*5) = 198.8 g

3 0

2 years ago

Identify the most and the least acidic compound in each of the following sets.

il63 [147K]

Answer:

See explanation

Explanation:

Our answer options for this question are:

a. 2-chlorobutanoic acid:_______ 2-chlorobutanoic acid:_______ 3-chlorobutanoic acid:______.

b. 2,4-dinitrobenzoic acid:______ p-nitrobenzoic acid:______ p-bromobenzoic acid:_______.

c. p-cyanobenzoic acid:________ benzoic acid:_______ p-aminobenzoic acid:______

We have to check each set of molecules

a. 2-chlorobutanoic acid, 3-chlorobutanoic acid

In this case, the difference between these molecules is the position of "Cl". If the chlorine atom is closer to the acid group, we will have a higher inductive effect. So, the bond O-H would be weaker and we will have more acidity. So, the molecule with more acidity is 2-chlorobutanoic acid and the less acidic would be 3-chlorobutanoic acid.

b. 2,4-dinitrobenzoic acid, p-nitrobenzoic acid, p-bromobenzoic acid

In this case, we have several structural differences. In all the structure, we have deactivating groups ( $Br$ and $NO_2$ ). If we have a deactivating group the acidity will increase. In the case of "Br", we have a weak deactivating, so, this will be the less acidic one (p-bromobenzoic acid)

in 2,4-dinitrobenzoic acid we have two deactivating groups, therefore, this would be the most acid compound.

c. p-cyanobenzoic acid, benzoic acid, p-aminobenzoic acid

On these molecules, we have several structural differences. In p-cyanobenzoic acid we have a deactivating group, therefore in this molecule we will have more acidity. In the p-aminobenzoic acid, we have an activating group, so, this would be the less acidic compound.

See figure 1

I hope it helps!

3 0

2 years ago

Element M reacts with oxygen to form an oxide with the formula MO. When MO is dissolved in water, the resulting solution is basi

Tpy6a [65]

Answer:

Calcium

Explanation:

Since the element reacts with oxygen to form an oxide with the formula MO, the charge on the element is +2.

Also, since the oxide MO when dissolved in water is basic, the metal is an alkali earth metal.

From the above conditions;

The metal is not arsenic because arsenic is a metalloid has the following oxides As₂O₃ and As₃O₅ and are respectively amphoteric and acidic in nature

The metal is not germanium because is a metalloid and even though germanium oxide has the formula GeO₂, it is amphoteric.

The metal is not chlorine because chlorine is a non-metal

The metal is definitely calcium because calcium oxide has the formula CaO and calcium is an alkaline earth metal.

The metal is not selenium because selenium is anon-meal and its oxide has the formula Se0₂ and is acidic

5 0

2 years ago