Answer:
The ΔH of the reaction is + 12.45 KJ/mol
Explanation:
Mass of water= 100ml = 100g. (You should always assume 1cm3 of water as 1g)
heat capacity of water = 4.18 Jk-1 Mol-1
Change in temperature = (19.86 - 25.00) = -5.14 K (This is an endothermic reaction because of the fall in temperature)
Molar mass of NaHCO3 = 84 g/mol
Mole of NaHCO3 = 14.5 / 84 = 0.173 mol
Step 1 : Calculate the heat energy (Q) lost by the water.
Q = M x C x ΔT
Q = -100 x 4.18 x (-5.14)
Q = 2148.5 joules
Q = 2.1485 K J
Step 2: Calculating the ΔH of the reaction?
ΔH = Q / number of moles of NaHCO3
ΔH = 2.1485 / 0.173
ΔH = 12.42 KJ/mol
Answer: A heterogeneous mixture is a mixture in which its components retain their identity.
Why: Heterogeneous mixtures have several parts which can't be separated, like an italian dressing. Therefore, it's prefix is (hetero), which means something along the lines of "different". In a homogeneous mixture, it can be separated, and the prefix (homo) means "same".
Answer:
133.74 L
Explanation:
First we <u>convert the given pressures and temperatures into atm and K</u>, respectively:
- 750.0 Torr ⇒ 750/760 = 0.9868 atm
- 20°C ⇒ 20+273.16 = 293.16 K
- 40°C ⇒ 40+273.16 = 313.16 K
Then we<u> use the PV=nRT formula to calculate the number of moles of helium in the balloon</u>, using<em> the data of when it was on the ground</em>:
- 0.9868 atm * 8.50 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 293.16 K
Then, knowing the value of n, we <u>use PV=nRT once again, this time to calculate V</u> using <em>the data of when the balloon was high up:</em>
- 0.550 atm * V = 2.866 mol * 0.082 atm·L·mol⁻¹·K⁻¹ * 313.16 K
The largest risks while designing a model to withstand a village include that the model does not mitigate the effects of the tsunami or only mitigates the effects partially, which would cause damages to the homes.
Designing a model to withstand the effect of any natural phenomenon such as an earthquake, fire or tsunami is not an easy task and will require the following cycle:
- Designing the model.
- Testing the model.
- Making changes or designing a new model.
In the case of a model for tsunamis, it is likely the following problems occur:
- The model does not protect the houses from tsunamis.
- The model does not protect the houses completely.
This would lead to negative effects such as:
- Damages in the houses.
- Dead or injured people.
- Destruction of infrastrcture.
Note: This question is incomplete because the context is missing; here is the missing part.
Protecting Your Model Village from Tsunamis this task, you will design a model village to withstand the effects of a tsunami.
Learn more about tsunami in: brainly.com/question/1126317
Answer:
Explanation:
To convert from moles to grams, we must use the molar mass (also known as the gram formula mass).
First, look up the molar masses of the elements in the formula.
- C: 12.011 g/mol
- H: 1.008 g/mol
- O: 15.999 g/mol
Next, multiply by the subscript, because it tells us the number of atoms of each element in the formula.
- C₉: 4(12.011 g/mol)= 108.099 g/mol
- H₈: 8(1.008 g/mol)= 8.064 g/mol
- O₄: 4(15.999 g/mol)= 63.996 g/mol
Add the values.
- 108.099 + 8.064+63.996=180.159 g/mol
Use this molar mass as a ratio.
Multiply by the given number of moles, 0.40
The units moles of aspirin cancel.
The original number of moles has 2 sig figs (4 and 0), so answer must have the same. For the number we calculated, it is the ones place. The 0 in the tenth place tells us to leave the 2.
