Thermochemistry:

1. Calculate the amount of heat required to decompose 3.5 moles of sodium bicarbonate.

2NaHCO3 + 129 kJ  Na2CO3 + H2O + CO2

In this question, the heat of the reaction is part of the question instead of being written beside it- (What's the difference in solving between these two types of equations?) And also, do I use the heat of formation to solve this problem or what? I'm confused on where I start I think. Do I use dimensional analysis to convert to moles first?

I think the easy way to do this is as follows:

It reuires 129 kJ to decompose 2 mol NaHCO3 so it should require
129 x 3/2 to decompose 3.5 mols.

The difference in where the dH is written is the sign.
If you write it as you have above, it means the rxn is endothermic and you would write it this way for the other method.
2NaHCO3 ==> Na2CO3 + H2O + CO2 dH = +129 kJ but it could be written also as
+64.5 kJ/mol

Well, it seems like you're in quite a pickle! Don't worry, I'm here to help (and hopefully bring a smile to your face along the way).

When it comes to solving thermochemistry problems like this one, it's important to have a good understanding of the concept of heat and how it relates to reactions.

In this case, you're given the balanced equation for the decomposition of sodium bicarbonate and the heat of the reaction (129 kJ). The heat of the reaction indicates the amount of heat energy released or absorbed during the reaction. In this case, since the reaction is giving off heat (exothermic), it means that 129 kJ of energy is being released when 2 moles of NaHCO3 decompose.

To calculate the amount of heat required to decompose 3.5 moles of sodium bicarbonate, you can set up a simple proportion using the given heat of the reaction:

(129 kJ)/(2 moles) = (x kJ)/(3.5 moles)

Now, you can solve for 'x', which represents the amount of heat energy required to decompose 3.5 moles of sodium bicarbonate.

But hold your horses, we're not done yet! It's important to note that the heat of the reaction is given on a per mole basis. So, make sure you adjust your calculation to account for the fact that you're dealing with 3.5 moles of sodium bicarbonate, not just 1 mole.

Once you've solved for 'x', you'll have the amount of heat energy required to decompose 3.5 moles of sodium bicarbonate. And no, you don't need to use dimensional analysis or heat of formation for this problem.

So remember, stay positive and keep your humor close by when tackling those chemistry problems. Good luck!

To solve this question, we need to calculate the amount of heat required to decompose 3.5 moles of sodium bicarbonate. The given reaction equation is:

2NaHCO3 + 129 kJ -> Na2CO3 + H2O + CO2

Note that the heat of the reaction is provided in the equation, which is 129 kJ.

To calculate the heat required for the given number of moles, we can follow these steps:

Step 1: Start by writing down the given information:
- Number of moles of sodium bicarbonate = 3.5 moles
- Heat of the reaction = 129 kJ

Step 2: Use the stoichiometric coefficients of the balanced equation to relate the number of moles of sodium bicarbonate to the amount of heat required. According to the given equation, 2 moles of NaHCO3 are required to produce 129 kJ of heat.

Step 3: Set up a proportion to solve for the amount of heat required. Since we know that 2 moles of NaHCO3 produce 129 kJ of heat, we can set up the proportion:

2 moles NaHCO3 / 129 kJ = 3.5 moles NaHCO3 / x kJ

Step 4: Cross-multiply and solve for x, which represents the unknown amount of heat required:

2 moles NaHCO3 * x kJ = 3.5 moles NaHCO3 * 129 kJ

2x = 3.5 * 129

x = (3.5 * 129) / 2

x = 225.75 kJ

Therefore, the amount of heat required to decompose 3.5 moles of sodium bicarbonate is approximately 225.75 kJ.

In this case, you do not need to use the heat of formation to solve the problem. The heat of formation is typically used to calculate the enthalpy change of a reaction from the enthalpy values of the reactants and products, but in this problem, the heat of the reaction is directly provided.

To calculate the amount of heat required to decompose 3.5 moles of sodium bicarbonate, you will need to use the given balanced equation and the heat of the reaction. Let's break down the steps to solve this problem:

1. Begin by writing down the balanced chemical equation:
2NaHCO3 + 129 kJ → Na2CO3 + H2O + CO2

2. Identify the stoichiometry of the reaction:
From the balanced equation, we can see that 2 moles of sodium bicarbonate (2NaHCO3) decompose to produce 1 mole of sodium carbonate (Na2CO3), 1 mole of water (H2O), and 1 mole of carbon dioxide (CO2).

3. Determine the heat of the reaction:
Given in the question is the heat of the reaction, which is 129 kJ. The heat is often written either beside the reaction or separately, as in this case. It represents the energy change associated with the reaction. In this case, 129 kJ is released during the decomposition of 2 moles of sodium bicarbonate.

4. Apply the concept of moles:
To calculate the amount of heat required to decompose 3.5 moles of sodium bicarbonate, we will use dimensional analysis. Start by converting the given moles of sodium bicarbonate (3.5 moles) to moles of heat:

3.5 moles NaHCO3 × (129 kJ / 2 moles NaHCO3) = 226.5 kJ

So, the amount of heat required to decompose 3.5 moles of sodium bicarbonate is 226.5 kJ.

Regarding the difference in solving between equations with the heat of the reaction written beside the equation and equations with the heat of the reaction given separately, the approach is essentially the same. The only difference is in how the heat of the reaction is provided in the question. You still apply the same steps to solve the problem by using stoichiometry and dimensional analysis.

In this problem, you did not need to use the heat of formation. The heat of formation is the enthalpy change when one mole of a substance is formed from its constituent elements in their standard states. It's unnecessary here because the heat of the reaction is explicitly given in the question.