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4 years ago

Why are most scientific questions carried out

Chemistry

1 answer:

Dimas [21]4 years ago

5 0

Answer:

Explanation:

A scientific investigation typically begins with observations. Observations often lead to questions. A hypothesis is a possible logical answer to a scientific question, based on scientific knowledge. A prediction is a statement that tells what will happen under certain conditions

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How much heat is required to vaporize 43.9 g of acetone at its boiling point?

bogdanovich [222]

The heat required to vaporize 43.9 g of acetone at its boiling point is calculated as below

the heat of vaporization of acetone at its boiling point is 29.1 kj/mole

find the moles of acetone = mass/molar mass
= 43.9g /58 g/mol =0.757 moles

heat (Q) = moles x heat of vaporization

= 29.1 kj/mole x 0.757 moles = 22.03 kj

5 0

3 years ago

Read 2 more answers

Given the following thermodynamic data, calculate the lattice energy of LiCl:

tiny-mole [99]

Answer:

$\boxed{\text{-862 kJ/mol}}$

Explanation:

One way to calculate the lattice energy is to use Hess's Law.

The lattice energy U is the energy released when the gaseous ions combine to form a solid ionic crystal:

Li⁺(g) + Cl⁻(g) ⟶ LiCl(s); U = ?

We must generate this reaction rom the equations given.

(1) Li(s) + ½Cl₂ (g) ⟶ LiCl(s); ΔHf° = -409 kJ·mol⁻¹

(2) Li(s) ⟶ Li(g); ΔHsub = 161 kJ·mol⁻¹

(3) Cl₂(g) ⟶ 2Cl(g) BE = 243 kJ·mol⁻¹

(4) Li(g) ⟶Li⁺(g) +e⁻ IE₁ = 520 kJ·mol⁻¹

(5) Cl(g) + e⁻ ⟶ Cl⁻(g) EA₁ = -349 kJ·mol⁻¹

Now, we put these equations together to get the lattice energy.

E/kJ

(5) Li⁺(g) +e⁻ ⟶ Li(g) 520

(6) Li(g) ⟶ Li(s) -161

(7) Li(s) + ½Cl₂(g) ⟶ LiCl(s) -409

(8) Cl(g) ⟶ ½Cl₂(g) -121.5

(9) Cl⁻(g) ⟶ Cl(g) + e⁻ +349

Li⁺(g) + Cl⁻(g) ⟶ LiCl(s) -862

The lattice energy of LiCl is $\boxed{\textbf{-862 kJ/mol}}$ .

3 0

3 years ago

A gas has a volume of 490. mL at a temperature of -35.0 degrees C. What volume would the gas occupy at 42.0 degrees Celsius? Ple

miskamm [114]

Answer:

648.5 mL

Explanation:

Here we will assume that the pressure of the gas is constant, since it is not given or specified.

Therefore, we can use Charle's law, which states that:

"For an ideal gas kept at constant pressure, the volume of the gas is proportional to its absolute temperature"

Mathematically:

$\frac{V}{T}=const.$

where

V is the volume of the gas

T is its absolute temperature

The equation can be rewritten as

$\frac{V_1}{T_1}=\frac{V_2}{T_2}$

where in this problem we have:

$V_1=490 mL$ is the initial volume of the gas

$T_1=-35.0^{\circ} + 273 = 238 K$ is the initial temperature

$T_2=42.0^{\circ}+273=315 K$ is the final temperature

Solving for V2, we find the final volume of the gas:

$V_2=\frac{V_1 T_2}{T_1}=\frac{(490)(315)}{238}=648.5 mL$

8 0

4 years ago

What is the mass of the hydrogen atoms in 1 mole of water

Katen [24]

Answer:

2.0158 grams

Explantion:

We are to find the mass of the hydrogen atoms in 1 mole of water.

We know that the formula of water is: $H_2O$

We can see, from the above mentioned formula, that water has 2 hydrpgen atoms.

From the periodic table, we get to know that Hydrogen has an atomic mass of 1.00794 grams.

As there are 2 atoms of hydrogen in water so $2 \times 1.00794 = 2.0158$ grams is the answer

3 0

3 years ago

Read 2 more answers

The temperature of a 100.0 g sample of water is raised from 30degrees celsius to 100.0 degrees celsius. How much energy is requi

worty [1.4K]

Answer:

29260J

Explanation:

Given parameters:

Mass of water sample = 100g

Initial temperature = 30°C

Final temperature = 100°C

Unknown:

Energy required for the temperature change = ?

Solution:

The amount of heat required for this temperature change can be derived from the expression below;

H = m c (ΔT)

H is the amount of heat energy

m is the mass

c is the specific heat capacity of water = 4.18J/g°C

ΔT is the change in temperature

Now insert the parameters and solve;

H = 100 x 4.18 x (100 - 30)

H = 100 x 4.18 x 70 = 29260J

6 0

3 years ago