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3 years ago

Whic number of the periodic table is the atomic number and which number is the atomic mass?

Chemistry

1 answer:

Anettt [7]3 years ago

5 0

Answer:

The mass number (represented by the letter A) is defined as the total number of protons and neutrons in an atom. Consider the element helium. Its atomic number is 2, so it has two protons in its nucleus.

The atomic mass of a single atom is simply its total mass and is typically expressed in atomic mass units or amu. By definition, an atom of carbon with six neutrons, carbon-12, has an atomic mass of 12 amu.

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Windblown________ can wear away rock

Bezzdna [24]

Windblown sand can wear away rock

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3 years ago

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What is the percent error for the experiment if the actual density is

OLga [1]

Answer:

<h3>The answer is 40.96%</h3>

Explanation:

The percentage error of a certain measurement can be found by using the formula

$P(\%) = \frac{error}{actual \: \: number} \times 100\% \\$

From the question

actual density = 2.49g/mL

error = 2.49 - 1.47 = 1.02

We have

$p(\%) = \frac{1.02}{2.49} \times 100 \\ = 40.96385542...$

We have the final answer as

Hope this helps you

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3 years ago

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A sample of copper absorbs 4.31E+1 kJ of heat, resulting in a temperature rise of 6.71E+1 °C. Determine the mass (in kg) of the

olga2289 [7]

Answer: 1.67 kg

Explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

$Q=m\times c\times \Delta T$

Q = Heat absorbed= $4.31\times 10^1kJ$ = $43100J$ (1kJ=1000J)

m= mass of substance = ?

c = specific heat capacity = $0.385J/g^0C$

Change in temperature , $\Delta T=T_f-T_i=6.71\times 10^1^0C=67.1^0C$

Putting in the values, we get:

$43100J=m\times 0.385J/g^0C\times 67.1^0C$

$m=1670g=1.67kg$ (1kg=1000g)

Thus the mass (in kg) of the copper sample is 1.67

3 0

3 years ago

The term “electricity” in referring to static electricity, means what

sladkih [1.3K]

Is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy.[1]

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3 years ago

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.

(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⁻ <u>+349</u>

Li⁺(g) + Cl⁻(g) ⟶ LiCl(s) -862

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

3 0

3 years ago