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2 years ago

My test is tomorrow and I'm confused about how to solve these. pls halp

Chemistry

1 answer:

Stels [109]2 years ago

5 0

Answer:

Explanation:

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BCAZ I don't know
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Al-Qaeda is the name of the group that fought against the Soviet-supported government in Afghanistan.

topjm [15]

False it is a terrorist group in Afghanistan and put 911 in ny

4 0

3 years ago

If you needed a 1.5 x 1 0-4 M solution of a compound that has a molar mass of 760 g/mol, what would it concentration be in part

motikmotik

Answer:

114 ppm

Explanation:

Data obtained from the question include:

Conc. of compound in mol/L = 1.5×10¯⁴ mol/L

Molar mass of compound = 760 g/mol

Conc. in ppm =..?

Next, we shall determine the concentration of the compound in grams per litre (g/L) . This is illustrated below:

Conc. in mol/L = conc. in g/L / Molar mass

1.5×10¯⁴ = conc. In g/L / 760

Cross multiply

Conc. in g/L = 1.5×10¯⁴ x 760

Conc. in g/L = 0.114 g/L

Next, we shall convert 0.114 g/L to milligrams per litre (mg/L). This is illustrated below:

1 g/L = 1000 mg/L

Therefore, 0.114 g/L = 0.114 x 1000 = 114 mg/L

Finally, we shall convert 114 mg/L to parts per million (ppm). This is illustrated below:

1 mg/L = 1 ppm

Therefore, 114 mg/L = 114 ppm

From the calculations made above,

1.5×10¯⁴ mol/L Is equivalent to 114 ppm.

6 0

3 years ago

(a) (1)

Elis [28]

Explanation:

The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase:

M(g) ® M+(g) + e-

It is possible to remove more electrons from most elements, so this quantity is more precisely known as the first ionization energy, the energy to go from neutral atoms to cations with a 1+ charge. The second ionization energy is the energy that is required to remove a second electron, to form 2+ cations from 1+ cations:

M+(g) ® M2+(g) + e-

The third ionization energy is the energy required to form 3+ cations:

M2+(g) ® M3+(g) + e-

and so on. Ionization energies are always positive numbers, because energy must be supplied (an endothermic energy change) to separate electrons from atoms. The second ionization energy is always larger than the first ionization energy, because it requires even more energy to remove an electron from a cation than it is from a neutral atom.

The first ionization energy varies in a predictable way across the periodic table. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.

From top to bottom in a group, orbitals corresponding to higher values of the principal quantum number (n) are being added, which are on average further away from the nucleus. Since the outermost electrons are further away, they are less strongly attracted by the nucleus, and are easier to remove, corresponding to a lower value for the first ionization energy.From left to right across a period, more protons are being added to the nucleus, but the number of electrons in the inner, lower-energy shells remains the same. The valence electrons feel a higher effective nuclear charge — the sum of the charges on the protons in the nucleus and the charges on the inner, core electrons. The valence electrons are therefore held more tightly, the atom decreases in size (see atomic radius), and it becomes increasingly difficult to remove them, corresponding to a higher value for the first ionization energy.

The following charts illustrate the general trends in the first ionization energy:

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8 0

3 years ago

Pentaborane-9, B5H9, is a colorless, highly reactive liquid that will burst into flame when exposed to oxygen. The reaction is 2

mina [271]

Answer: The amount of energy released per gram of $B_5H_9$ is -71.92 kJ

Explanation:

For the given chemical reaction:

$2B_5H_9(l)+12O_2(g)\rightarrow 5B_2O_3(s)+9H_2O(l)$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f_{(product)}]-\sum [n\times \Delta H^o_f_{(reactant)}]$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(5\times \Delta H^o_f_{(B_2O_3(s))})+(9\times \Delta H^o_f_{(H_2O(l))})]-[(2\times \Delta H^o_f_{(B_5H_9(l))})+(12\times \Delta H^o_f_{(O_2(g))})]$

Taking the standard enthalpy of formation:

$\Delta H^o_f_{(B_2O_3(s))}=-1271.94kJ/mol\\\Delta H^o_f_{(H_2O(l))}=-285.83kJ/mol\\\Delta H^o_f_{(B_5H_9(l))}=73.2kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(5\times (1271.94))+(9\times (-285.83))]-[(2\times (73.2))+(12\times (0))]\\\\\Delta H^o_{rxn}=-9078.57kJ$

We know that:

Molar mass of pentaborane -9 = 63.12 g/mol

By Stoichiometry of the reaction:

If 2 moles of $B_5H_9$ produces -9078.57 kJ of energy.

Or,

If $(2\times 63.12)g$ of $B_5H_9$ produces -9078.57 kJ of energy

Then, 1 gram of $B_5H_9$ will produce = $\frac{-9078.57kJ}{(2\times 63.12)}\times 1g=-71.92kJ$ of energy.

Hence, the amount of energy released per gram of $B_5H_9$ is -71.92 kJ

8 0

3 years ago

A gas bottle contains 8. 61×1023 oxygen molecules at a temperature of 359. 0 k. what is the thermal energy of the gas? (you migh

Cloud [144]

A gas bottle contains 8. 61×1023 oxygen molecules at a temperature of 359. 0 k then the thermal energy of the gas is 6.35KJ.

<h3>What is thermal energy? </h3>

Thermal energy is the energy contained within a system which is responsible for its temperature. Heat is also termed as flow of thermal energy.

Thermal energy is directly proportional to the temperature. As temperature increase thermal energy increases.

Given,

temperature = 395K

Number of oxygen molecules= 8.61 × 10^(23)

Firstly we will calculate the number of moles = N/A

where A is the avagadro number = 6.022 × 10^(23)

number of moles = 8.61 × 10^(23)/6.022 ×10^(23)

number of moles = 1.42moles

Using the energy equation,

E = 3/2 × nRT

where R is the gas constant = 8.314J/molK

E = 3/2 × 1.42 × 8.314 × 359

= 6357.4J

= 6.35KJ

Thus, we found that the thermal energy of the gas is 6.35KJ.

learn more about thermal energy:

brainly.com/question/2409175

#SPJ4

5 0

1 year ago