CHEMISTRY HIGH SCHOOL

A)1.5 km + 4.32 km
b) 4.6 cm x 1.586 cm

Answers

Answer 1
Answer:

Answer:

a. 5.82km

b. 7.2956cm

Explanation:

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According to Table I, which equation represents a change resulting in the greatest quantity of energy released? 2C(s) + 3H2(g) → C2H6(g) 2C(s) + 2H2(g) → C2H4(g) N2(g) + 3H2(g) → 2NH4(g) N2(g) + O2(g) → 2NO(g)

Answers

The answer is N2+3H2->2NH4. You can get the heat change on Table I. After checking the table I, you can get the ΔH for every reaction. The positive sign means absorbing energy and negative sign means releasing energy.

List two greenhouse gases .

Answers

Answer: carbon dioxide, methane

Explanation:
1) Methane
2)Carbon dioxide

A sample of nitric acid contains both H3O ions and NO3 ions. This sample has a pHvalue of 1.

Write a name of the positive ion present in this sample.

Answers

Answer : The name of positive ion present in this sample is, hydronium ion.

Explanation :

For formation of a neutral ionic compound, the charges on cation and anion must be balanced.

The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

Ion : An ion is formed when an atom looses or gains electron.

When an atom looses electrons, it will form a positive ion known as cation.

When an atom gains electrons, it will form a negative ion known as anion.

As per question, hydronium ion or hydrogen ion is having an oxidation state of +1 called as H_3O^(+) or H^+ cation and nitrate ion NO_3^(-) is an anion with oxidation state of -1.

Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral HNO_3.

Hence, the name of positive ion present in this sample is, hydronium ion.

Propane (C3H8) reacts with oxygen gas to produce carbon dioxide & water. How many grams of oxygen are needed to oxidize 12.5g of propane (C3H8)? a) 1.8

b) 22.7

c) 55.6

d) 31.8

e) 45.5

Answers

The amount of oxygen needed to oxidize 12.5g of propane is 45.5g.

What is stoichiometry in chemistry?

Stoichiometry is the calculation of the quantitative relationships between the amounts of reactants and products in chemical reactions.

The balanced chemical equation for the combustion of propane is:

C3H8 + 5O2 → 3CO2 + 4H2O

To calculate the amount of oxygen needed to react with 12.5g of propane, we need to use stoichiometry and the molar mass of propane. The molar mass of propane is 44.1 g/mol.

First, we need to convert the mass of propane to moles:

12.5 g C3H8 × (1 mol C3H8 / 44.1 g C3H8) = 0.283 mol C3H8

According to the balanced equation, 5 moles of oxygen are required to react with 1 mole of propane. So, we can calculate the amount of oxygen needed as follows:

0.283 mol C3H8 × (5 mol O2 / 1 mol C3H8) = 1.415 mol O2

Finally, we can convert the moles of oxygen to grams using the molar mass of oxygen, which is 32.0 g/mol:

1.415 mol O2 × 32.0 g O2/mol = 45.1 g O2

Therefore, the answer is e) 45.5 g of oxygen is needed to oxidize 12.5g of propane (C3H8).

Learn more about Stoichiometry here:

brainly.com/question/30215297?

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Neopentyl alcohol, (ch3)3cch2oh, cannot be dehydrated to an alkene without rearrangement. what is the chief product of dehydration?

Answers

Dehydration is removal of water.

In alcohols dehydration is α-β elimination or 1,2 elimination, it means the hydroxyl group will be removed from α-carbon while the hydrogen will be removed from near by carbon.

In case of neopentyl alcohol there is no β hydrogen present on the β carbon [as shown in figure].

The only possible way for it to undergo dehydration is by rearrangement.

The process or mechanism can be understood as:


so the chief product is 2-methylbut-2-ene

Which of the following circumstances will result in a reaction that is spontaneous only at low temperatures?A.) positive enthalpy change and positive entropy change
B.) negative enthalpy change and negative entropy change
C.) positive enthalpy change and negative entropy change
D.) negative enthalpy change and positive entropy change

Answers

Answer: B.) negative enthalpy change and negative entropy change

Explanation:

According to Gibb's equation:

\Delta G=\Delta H-T\Delta S

\Delta G = Gibbs free energy  

\Delta H = enthalpy change

\Delta S = entropy change  

T = temperature in Kelvin

\Delta G= +ve, reaction is non spontaneous

\Delta G= -ve, reaction is spontaneous

\Delta G= 0, reaction is in equilibrium

Thus when \Delta H = -ve

\Delta S = -ve

\Delta G=(-ve)-T(-ve)

\Delta G=(-ve)(+ve)=-ve   only at low temperature

Reaction is spontaneous only if temperature is low.
D) negative enthalpy and positive entropy,
since the formula G=H-TS when a reaction is spontaneous then G must be negative, and if values of t are low then the only time it is guaranteed to be a negative G value is if H is positive and S is negative
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