Laws differ from theories because laws do not provide

TiliK225 [7]

Answer: -22.2 kJ

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps. SGDSDGSDGSDGgsg

According to Hess’s law, the chemical equation can be treated as algebraic expressions and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

(1) $2Fe(s)+O_2(g)\rightarrow 2FeO(s)$ $\Delta H_1=-544.0kJ$

(2) $4Fe(s)+O_2(g)\rightarrow 2Fe_2O_3(s)$ $\Delta H_2=-1648.4kJ$

(3) $Fe_3O_4(s)\rightarrow 3Fe(s)+2O_2(g)$ $\Delta H=+1118.4kJ$

Reversing 1 ,2 and 3 and halving 1 and 2 and then adding we get net equation:

(4) $Fe_2O_3(s)+FeO(s)\rightarrow Fe_3O_4(s)$ $\Delta H_4=?$

$\Delta H_4=\frac{-\Delta H_1}{2}+\frac{-\Delta H_2}{2}+(-\Delta H_3)=\frac{544.0}{2}+\frac{1648.4}{2}+(-1118.4)=-22.2kJ$

Therefore, the heat of reaction, ΔH, for the reaction is -22.2 kJ

6 0

3 years ago

The closeness of a measurement to its actual value is a measure of its

Vikki [24]

The answer is letter D

8 0

3 years ago

How does a catalyst influence a chemical reaction.

UNO [17]

Answer: C.It provides an alternative energy pathway for the reaction to proceed.

Explanation:

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.

A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and more molecules convert to products.

Thus catalyst speeds up the reaction and does not increase the total amount of product formed.

The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.

3 0

3 years ago

Read 2 more answers

The term El Nino/Southern Oscillation refers to the occurrence of warmer than normal sea surface temperatures in the Eastern Pac

Amiraneli [1.4K]

Answer:

True

Explanation:

The El Nino/Southern Oscillation occurs in between the three phases Neutral, La Nina or El Nino.

The humboldt current takes cold water to South America's west coast to the tropics from the Southern Ocean. Because of the welling which takes place in Peru this process is enhanced. Due to the trade winds near the equator the cold water travels west where it heats up due to the sun. This makes the water of the western Pacific warmer.

6 0

4 years ago

A weather balloon is filled with helium that occupies a volume of 5.37 104 L at 0.995 atm and 32.0°C. After it is released, it r

svp [43]

Answer:

The new volume is 63583 L

Explanation:

Step 1: Data given

The initial volume of the balloon = 5.37 * 10^4 L

The initial pressure = 0.995 atm

The initial temperature = 32.0 °C = 305.15 K

The pressure decreased to 0.720 atm

The temperature decreased to -11.7 °C = 261.45 K

Step 2: Calculate the new volume

P1*V1 / T1 = P2*V2/T2

⇒with P1 = the initial pressure = 0.995 atm

⇒with V1 = the initial volume = 5.37 *10^4 L

⇒with T1 = the initial temperature = 305.15 K

⇒with P2 = the decreased pressure = 0.720 atm

⇒with V2 = the new volume = TO BE DETERMINED

⇒with T2 = the decreased temperature : 261.45 K

(0.995 * 5.37*10^4)/305.15 = (0.720 * V2) / 261.45

V2 = 63583 L

The new volume is 63583 L

8 0

3 years ago