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2 years ago

Which statement accurately compares the trends in atomic number and atomic mass in the periodic table?

Chemistry

2 answers:

Kruka [31]2 years ago

7 0

Answer : The correct option is, (C) Both the atomic mass and the atomic number increase from left to right.

Explanation :

The general trend of atomic number and atomic mass in the periodic table is,

Both atomic number and atomic mass increase from left to right and decreases from right to left in the periodic table due to the addition of the number of neutrons and the number of protons in the nucleus.

Hence, the correct option is, (C) Both the atomic mass and the atomic number increase from left to right.

slava [35]2 years ago

4 0

C.Both the atomic mass and the atomic number increase from left to right.

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Butane (c4h10) undergoes combustion in excess oxygen to generate gaseous carbon dioxide and water. given δh°f[c4h10(g)] = –124.7

vagabundo [1.1K]

The value of Δ H butane (g) = -124.7 kJ/mol

The value of Δ H CO2 (g) = -393.5 kJ/mol

The value of Δ H H2O (g) = -241.8 kJ/mol

Mass of butane, m = 8.30 gm

Molar mass of butane is 58 gm/mol

Consider the reaction,

C₄H₁₀ + 6.5 O₂ = 4CO₂ + 5H₂O

Calculating the value of Δ H° rxn:

ΔH°rxn = ∑nH° f (products) - ∑nH° f (reactants)

Substituting the values we get,

Δ H° rxn = 4 (-393.5) + 5 (-241.8) - (-124.7)

= -1574 -1209 + 124.7

= -2783 - 124.7

= -2658.3 kJ/mol

Now, calculate the number of moles of butane in 8.30 gm.

Number of moles = mass/molar mass

= 8.30 / 58

= 0.143 moles

Thus, the total energy released in the reaction is,

Q = number of moles × ΔH° rxn

= 0.143 × (2658.3)

= 380.14 kJ

Hence, the total heat released in the reaction is 380.14 kJ.

6 0

2 years ago

Given six molecules, identify the molecules with polar bonds and the molecules that are polar.CCl4, CH3Cl, H20, CO2, O2

Nikitich [7]

Answer:

Non-polar compounds: $CCl_4$ , $O_2$ , $CO_2$

Polar compounds: $CH_3Cl$ , $H_2O$

Explanation:

For this question, we must start with the Lewis structure for each molecule and then we can do their respective analysis:

-) $CCl_4$

In this case, we have 4 equal atoms attached to the central atom. Therefore, we have the same magnitude of electronegativity. Chlorine atoms have different and opposite directions. Therefore due to the orientation the dipole moments cancel and the net dipole moment will be zero and the molecule will be non-polar.

-) $O_2$

In this case, we have a linear structure in which the magnitude of the dipole moment is the same, but the direction is the opposite. Therefore the dipole moments are canceled and the molecule will be non-polar.

-) $CO_2$

In this case, we also have a linear structure in which the magnitude of the dipole moment is the same, but the direction is the opposite. Therefore the dipole moments are canceled and the molecule will be non-polar.

-) $CH_3Cl$

For this molecule, we have a different atom. The hydrogen atom, therefore the magnitude of one of the atoms attached to the central atom is different and the magnitude of the net dipole moment will be different from zero and the molecule will be polar.

-) $H_2O$

For this molecule, due to the structure of the molecule, the dipole moments of oxygens will not have a totally opposite configuration. Therefore, the net dipole moment will be different from zero and the molecule will be polar.

See figure 1 to further explanations

I hope it helps!

5 0

2 years ago

During a titration the following data were collected. A 10. mL portion of an unknown monoprotic acid solution was titrated with

Liula [17]

Answer:

8.0 moles

Explanation:

Since the acid is monoprotic, 1 mole of the acid will be required to stochiometrically react with 1 mole of NaOH.

Using the formula: $\frac{concentration of acid X volume of acid}{concentration of base X volume of base} = \frac{mole of acid}{mole of base}$

Concentration of acid = ?

Volume of acid = 10 mL

Concentration of base = 1.0 M

Volume of base = 40 mL

mole of acid = 1

mole of base = 1

Substitute into the equation:

$\frac{concentration of acid X 10}{1.0 X 40} = \frac{1}{1}$

Concentration of acid = 40/10 = 4.0 M

To determine the number of moles of acid present in 2.0 liters of the unknown solution:

Number of moles = Molarity x volume

molarity = 4.0 M

Volume = 2.0 Liters

Hence,

Number of moles = 4.0 x 2.0 = 8 moles

8 0

2 years ago

A 2135 cm3 sample of dry air has a pressure of 98.4 kpa at 127 degrees Celsius. What is the volume of the sample if the Temperat

kykrilka [37]

the equation is p1 x v1 divided by T1 = p1 x v2 = T2 but since the pressure is kept constant you do not even need it so the equation would now be v1 divided by t1 = v2 divided by t2

2135 cm3 divided by 127 degrees celcius = x divided by 206

answer: 3460 cm3

7 0

2 years ago

Read 2 more answers

A sample from solution a and solution b were each tested with blue colored glucose indicator solution before the solutions were

vova2212 [387]

With the given problem you gave here, I can't answer the question because I need more details. Luckily, I found a similar problem that's provided with a diagram and a table shown in the attached picture.

This test is called the Benedict's test which is used as test for presence of sugars. If the solution contains sugar, like glucose, the solution would turn from blue to red. If not, it would stay blue. Therefore, the correct results would be that in row 3.

3 0

2 years ago