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3 years ago

Using the following thermochemical data, what is the change in enthalpy for the following reaction?

1 answer:

5 0

In calculating the change in enthalpy in a certain reaction, it is important to remember that it is the sum of the enthapy of formation for the substances involved in the reaction.

CaO(s)+2HCl(aq)→CaCl2(aq)+H2O(l) ΔH= –186kJ
Ca(OH)2(aq) → CaO(s)+H2O(l) ΔH= 65.1 kJ
Ca(OH)2(aq) + 2HCl(aq) → CaCl2(aq) + 2H2O(l) ΔH= -120.9 kJ

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Hemoglobin, a protein in red blood cells, carries O2 from the lungs to the body's cells. Iron (as ferrous ion, Fe2+) makes up 0.

levacccp [35]

Answer: The number of $Fe^{2+}$ ions in one molecule of hemoglobin are 4.

Explanation:

According to mole concept:

1 mole of an element contains $6.022\times 10^{23}$ number of atoms.

We are given:

Mass of 1 mole of hemoglobin = $6.8\times 10^4g$

Using above equation:

$6.022\times 10^{23}$ number of molecules have a mass of $6.8\times 10^4g$

So, 1 molecule of hemoglobin will have a mass of $\frac{6.8\times 10^4g}{6.022\times 10^{23}}\times 1=1.129\times 10^{-19}g$

It is also given that 0.33 mass % of hemoglobin has $Fe^{2+}$ ions

So, mass of $Fe^{2+}$ ions will be = $\frac{0.33}{100}\times 1.129\times 10^{-19}g=3.7257\times 10^{-22}g$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of iron ion = $3.7257\times 10^{-22}g$

Molar mass of iron ion = 55.85 g/mol

Putting values in above equation, we get:

$\text{Moles of }Fe^{2+}\text{ ion}=\frac{3.7257\times 10^{-22}g}{55.85g/mol}=6.67\times 10^{-24}mol$

Using mole concept:

1 mole of an element contains $6.022\times 10^{23}$ number of atoms.

So, $6.67\times 10^{-24}$ moles of hemoglobin will contain = $6.022\times 10^{23}\times 6.67\times 10^{-24}=4$

Hence, the number of $Fe^{2+}$ ions in one molecule of hemoglobin are 4.

8 0

3 years ago

24.568 cm of chlorine at 25° C will occupy what volume

Vlad1618 [11]

Answer:

20.446cm3

Explanation:

The following were obtained from the question given:

V1 (initial volume) = 24.568 cm3

T1 (initial temperature) = 25°C = 25 + 273 = 298K

T2 (final temperature) = - 25°C = - 25 + 273 = 248K

V2 (final volume) = ?

Since the pressure is constant, the gas is obeying Charles' law. With the Charles' law equation V1/T1 = V2/T2, we can easily calculate the final volume as follow:

V1/T1 = V2/T2

24.568/298 = V2/248

Cross multiply to express in linear form as shown below:

298 x V2 = 24.568 x 248

Divide both side by 298

V2 = (24.568 x 248) /298

V2 = 20.446cm3

From the calculations made above, the volume of the gas at -25°C is 20.446cm3

5 0

4 years ago

Calculate the molecular mass of Co(NO3)2 with steps please

Nana76 [90]

Answer:

$182.933~ \text{g mol}^{-1}$

Explanation:

$\text{Atomic mass of cobalt(Co)} = 58.933~u\\\\\text{Atomic mass of nitrogen(N)}= 14~u\\\\\text{Atomic mass of oxygen(O)}=16~u\\\\\text{Molar mass of}~ \text{Co}\left(\text{NO}_3} \right)_2 = 58.933 + 2(14 +16 \times 3)~ \text{g mol}^{-1}\\\\~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=(58.933 + 124)~ \text{g mol}^{-1}\\\\~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=182.94~ \text{g mol}^{-1}$

4 0

2 years ago

A car battery produces electrical energy with the following chemical reaction.

jok3333 [9.3K]

It has a 1:2 ratio
If you look at the start of PbO2 it does not have a number so that is the one and if you look at 2H2O that has a 2 in front so that is where you get the 1:2 ratio

3 0

3 years ago

Which type of bond happens when electrons are transferred

Lynna [10]

Ionic bonding is the answer

3 0

3 years ago