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3 years ago

Which of the following substances would complete a circuit and allow electricity to flow?

Chemistry

1 answer:

Elza [17]3 years ago

5 0

The substances which allow the current to flow in the circuit are:

Lithium bromide in a solution and Graphite.

Lithium bromide can be pass the current in the circuit, due to the ability to form ions in the solution Li⁺ and Br⁻ which are mobile and can transport the electrical charge.

In the graphite because of the presence of delocalised electrons, each carbon atom forms three covalent bonds with three other carbon atoms, it conducts electrical current.

In the case of potassium chloride lattice there are in a solid form and the atoms are not mobile so they can not form ions. In the diamond all the carbon valences are satisfied so the electrical charge can not be transported.

Nitric oxide in a solution is isolated and can not transport the electrical current due to its inability of the to form ions .

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Methanol, ethanol, and n−propanol are three common alcohols. When 1.00 g of each of these alcohols is burned in air, heat is lib

KengaRu [80]

Answer:

For methanol: Heat of combustion = -22.6 kJ / 0.0312 moles = -724.3590 kJ/mol (negative sign signifies release of heat)

For ethanol: Heat of combustion = -29.7 kJ / 0.0217 moles = -1368.6636 kJ/mol (negative sign signifies release of heat)

For propanol: Heat of combustion = -33.4 kJ / 0.0166 moles = -2012.0482 kJ/mol (negative sign signifies release of heat)

Explanation:

Given:

Mass of Methanol = 1.0 g

Mass of ethanol = 1.00 g

Mass of n-propanol = 1.00 g

For methanol:

2 CH₃OH + 3 O₂ ----> 2 CO₂ + 4 H₂O, ∆H₀ = -22.6 kJ/g (negative sign signifies release of heat)

1 g of methanol on combustion gives 22.6 kJ of energy

Calculation of moles of methanol:

$moles=\frac{Mass(m)}{Molar\ mass (M)}$

Molar mass of methanol = 32.04 g/mol

Thus moles of methanol = 1 g/ (32.04 g/mol) = 0.0312 moles

Hence energy in kJ/mol:

Heat of combustion = -22.6 kJ / 0.0312 moles = -724.3590 kJ/mol (negative sign signifies release of heat)

For ethanol:

C₂H₅OH + 3 O₂ ----> 2 CO₂ + 3 H₂O, ∆H₀ = -29.7 kJ/g (negative sign signifies release of heat)

1 g of ethanol on combustion gives 29.7 kJ of energy

Calculation of moles of ethanol:

$moles=\frac{Mass(m)}{Molar\ mass (M)}$

Molar mass of ethanol = 46.07 g/mol

Thus moles of ethanol = 1 g/ (46.07 g/mol) = 0.0217 moles

Hence energy in kJ/mol:

Heat of combustion = -29.7 kJ / 0.0217 moles = -1368.6636 kJ/mol (negative sign signifies release of heat)

For propanol:

2 C₃H₇OH + 9 O₂ ----> 6 CO₂ + 8 H₂O, ∆H₀ = -33.4 kJ/g , (negative sign signifies release of heat)

1 g of methanol on combustion gives 33.4 kJ of energy

Calculation of moles of methanol:

$moles=\frac{Mass(m)}{Molar\ mass (M)}$

Molar mass of methanol = 60.09 g/mol

Thus moles of methanol = 1 g/ (60.09 g/mol) = 0.0166 moles

Hence energy in kJ/mol:

Heat of combustion = -33.4 kJ / 0.0166 moles = -2012.0482 kJ/mol (negative sign signifies release of heat)

5 0

3 years ago

Calculate Î”HÂ° = for the chemical reaction

babymother [125]

Answer: $\Delta H^0$ for the reaction $Cl_2(g)+F_2(g)\rightarrow 2ClF(g)$ is -108kJ

Explanation:

The balanced chemical reaction is,

The expression for enthalpy change is,

$\Delta H=[n\times B.E_{reactants}]-[n\times B.E{products}]$

where, n = number of moles

Now put all the given values in this expression, we get

$\Delta H=[1\times B.E_{Cl_2}+1\times B.E_{F_2}]-[2\times B.E_{ClF}]$

$\Delta H=[(1\times 243)+(1\times 159)]-[2\times 255]$

$\Delta H=-108kJ$

Thus $\Delta H^0$ for the reaction $Cl_2(g)+F_2(g)\rightarrow 2ClF(g)$ is -108kJ

4 0

3 years ago

5. A 5.00 g sample of an unknown substance was heated from 25.2 C to 55.1 degrees * C , and it required 133 to do so. Identify t

Leviafan [203]

Answer:

Aluminum

Explanation:

Given

$T_1 = 25.2^oC$

$T_2 = 55.1^oC$

$m = 5.00g$

$\triangle Q= 133J$

See attachment for chart

Required

Identify the unknown substance

To do this, we simply calculate the specific heat capacity from the given parameters using:

$c = \frac{\triangle Q}{m\triangle T}$

This gives:

$c = \frac{\triangle Q}{m(T_2 - T_1)}$

So, we have:

$c = \frac{133J}{5.00g * (55.1C - 25.2C)}$

$c = \frac{133J}{5.00g * 29.9C}$

$c = \frac{133J}{149.5gC}$

$c = 0.89\ J/gC$

From the attached chart, we have:

$Al(s) = 0.89\ J/gC$ --- The specific heat capacity of Aluminum

Hence, the unknown substance is Aluminum

7 0

3 years ago

Another structure that most cells have in common is a _____________________ in the center of the cell, which contains the bluepr

alexdok [17]

Answer:

NUCLEUS

Explanation:

Firstly, the BLUEPRINT of life in living cells is the DNA, which stores the information that encodes the synthesis of products (proteins) that are needed by the cell for growth and reproduction. This DNA is located in a structure in eukaryotic cells called NUCLEUS.

The NUCLEUS is the organelle present in the center of eukaryotic cells, which which contains DNA, which is regarded as the blueprints for the cell's growth and reproduction. Note that, the most cells being referred to in this question are EUKARYOTIC CELLS as prokaryotic cells do not contain a NUCLEUS.

6 0

3 years ago

How many isomers of dichloroethylene have a zero dipole moment?

Effectus [21]

There are three dichloroethylen isomers: 1,1, dichloroethylene; 1,2 cis dichloroethylene and 1,2 trans dichloroethyelene.

1,1 dichlorothylene have two Cl - C dipoles on the same side of the molecule and they do not cancel each other, so this isomer has a net dipole moment.

1,2 cis dichloroethylene has two Cl - C dipoles on the same plane so they do not cancel each other, and this isomer also has a net dipole moment.

1,2 trans dichloroethylene has two Cl - C dipoles on different planes and they cancel each other. So this isomer has a zero dipole moment.

The answer is that one isomer of dichloroethylene has a zero dipole moment.

6 0

4 years ago

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