How many boxes of B would be required to make 30 grams of C?

Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(

kkurt [141]

Answer: The $\Delta H^o_{rxn}$ for the reaction is 72 kJ.

Explanation:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)$ $\Delta H^o_{rxn}=?$

The intermediate balanced chemical reaction are:

(1) $2Sr(s)+O_2(g)\rightarrow 2SrO(s)$ $\Delta H_1=-1184kJ$

(2) $SrO(s)+CO_2(g)\rightarrow SrCO_3(s)$ $\Delta H_2=-234kJ$ ( × 2)

(3) $CO_2(g)\rightarrow C(s)+O_2(g)$ $\Delta H_3=394kJ$ ( × 2)

The expression for enthalpy of the reaction follows:

$\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[2\times (-\Delta H_2)]+[2\times (\Delta H_3)]$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times (-1184))+(2\times -(-234))+(2\times (394))]=72kJ$

Hence, the $\Delta H^o_{rxn}$ for the reaction is 72 kJ.

4 0

3 years ago

A hydrate is compound that included water molecules within its crystal structure. During an experiment to determine the percent

stellarik [79]

Answer:

The percent by mass of water in this crystal is:

21.4%

Explanation:

This exercise can be easily solved using a simple rule of three where the initial weight of the hydrated crystal (6,235 g) is taken into account as 100% of the mass, and the percentage to which the mass of 4.90 g corresponds (after getting warm). First, the values and unknown variable are established:

6,235 g = 100%
4.90 g = X

And the value of the variable X is found:

X = (4.90 g * 100%) / 6,235 g
X = approximately 78.6%.

The calculated value is not yet the percentage of the water, since the water after heating the glass has evaporated, therefore, the remaining percentage must be taken, which can be calculated by subtraction:

Water percentage = Total percentage - Percentage after heating.
Water percentage = 100% - 78.6% = 21.4%

4 0

4 years ago

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How much energy (in Joules) is needed to increase the temperature of 25 grams of glass by 5.0C. Aluminum Iron Glass Copper Water

vitfil [10]

Answer:

25 grams of glass by 5.oc aluminium iron glass copper water

4 0

3 years ago

Identify the correct descriptions of beta particles.

FrozenT [24]

Answer:

a. A beta particle has a negative charge. d. A beta particle is a high-energy electron.

Explanation:

Identify the correct descriptions of beta particles.

a. A beta particle has a negative charge. YES. A beta particle is originated in the following nuclear reaction: ¹₀n ⇒ ¹₁H + ⁰₋₁e (beta particle.)

b. A beta particle contains neutrons. NO. It is a electron originated in the nucleus.

c. A beta particle is less massive than a gamma ray. NO. Gamma rays don't have mass while a beta particle has a mass which is half of one thousandth of the mass of a proton.

d. A beta particle is a high-energy electron. YES. Beta particles are nuclear originated hig-energy electrons.

6 0

3 years ago

At which condition will the entropy of a pure solid be zero?

miss Akunina [59]

The condition at which the entropy of a pure solid will be zero is when a substance is at absolute zero. Absolute zero is the lowest temperature that is theoretically possible, at which the motion of particles which constitutes heat would be minimal. It is zero on the Kelvin scale, equivalent to −273.15°C.

5 0

3 years ago

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