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3 years ago

Question 1 Review Which laboratory equipment is correctly paired with the unit it measures?

Chemistry

1 answer:

Bad White [126]3 years ago

6 0

Answer:

Cilindros graduados

Explanation:

Son una herramienta de medición primaria para el volumen de un líquido, y tiene varias marcas hacia arriba y hacia abajo a lo largo del contenedor con incrementos específicos. Los cilindros graduados vienen en muchos tamaños; entre más pequeños sean de diámetro, más específicas serán las mediciones de volumen. Al leer el volumen de un cilindro graduado, notarán que el líquido parece tener una muesca; el líquido alrededor de los bordes será más alto que el líquido en el centro, inclinándose hacia abajo como los lados de un trampolín cuando alguien está parado en el medio. Esto se llama el menisco. Alineen el punto más bajo del menisco con la marca más cercana, manteniendo el nivel del cilindro para leer correctamente el volumen.

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How many moles of sodium chloride are in 828 mL of a 1.42 M solution of sodium chloride?

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3 years ago

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Tell the teacher, do NOT clean it up yourself.

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3 years ago

Can you make a prediction about which ionic compounds will cause an increase or decrease in the temperature of the solution when

mel-nik [20]

Answer:

If the hydration energy is greater than the lattice energy of the solute, then the enthalpy of solution is positive(exothermic), otherwise it is negative(exothermic).

Explanation:

The process of dissolving can be endothermic (temperature goes down) or exothermic (temperature goes up).

When water dissolves a substance, the water molecules attract and “bond” to the particles (molecules or ions) of the substance causing the particles to separate from each other.

The “bond” that a water molecule makes is not a covalent or ionic bond. It is a strong attraction caused by water’s polarity.

It takes energy to break the bonds between the molecules or ions of the solute.

In an ionic solution, the existence of the lattice energy and hydration energy largely determines if the solution is exothermic or endothermic.

Lattice Energy: It is a measure of the cohesive forces that bind ions.

Hydration energy: is the amount of energy released when one mole of ions undergo hydration.

Energy is released when water molecules bond to the solute molecules or ions.

If it takes more energy to separate the particles of the solute than is released when the water molecules bond to the particles, then the temperature goes down (endothermic) i.e hydration energy is greater than the lattice energy.

If it takes less energy to separate the particles of the solute than is released when the water molecules bond to the particles, then the temperature goes up (exothermic) i.e hydration energy is less than lattice energy.

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3 years ago

For most solids at room temperature, the specific heat is determined by oscillations of the atom cores in the lattice (each osci

Cloud [144]

Answer:

The specific heat of copper is $C= 392 J/kg\cdot ^o K$

Explanation:

From the question we are told that

The amount of energy contributed by each oscillating lattice site is $E =3 kT$

The atomic mass of copper is $M = 63.6 g/mol$

The atomic mass of aluminum is $m_a = 27.0g/mol$

The specific heat of aluminum is $c_a = 900 J/kg-K$

The objective of this solution is to obtain the specific heat of copper

Now specific heat can be defined as the heat required to raise the temperature of 1 kg of a substance by $1 ^o K$

The general equation for specific heat is

$C = \frac{dU}{dT}$

Where $dT$ is the change in temperature

$dU$ is the change in internal energy

The internal energy is mathematically evaluated as

$U = 3nk_BT$

Where $k_B$ is the Boltzmann constant with a value of $1.38*10^{-23} kg \cdot m^2 /s^2 \cdot ^o K$

T is the room temperature

n is the number of atoms in a substance

Generally number of atoms in mass of an element can be obtained using the mathematical operation

$n = \frac{m}{M} * N_A$

Where $N_A$ is the Avogadro's number with a constant value of $6.022*10^{23} / mol$

M is the atomic mass of the element

m actual mass of the element

So the number of atoms in 1 kg of copper is evaluated as

$m = 1 kg = 1 kg * \frac{10000 g}{1kg } = 1000g$

The number of atom is

$n = \frac{1000}{63.6} * (6.0*0^{23})$

$= 9.46*10^{24} \ atoms$

Now substituting the equation for internal energy into the equation for specific heat

$C = \frac{d}{dT} (3 n k_B T)$

$=3nk_B$

Substituting values

$C = 3 (9.46*10^{24} )(1.38 *10^{-23})$

$C= 392 J/kg\cdot ^o K$

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Advocard [28]

The correct answer for, An element with the smallest anionic (negative-ionic) radius would be found on the periodic table in, is <span>Group 17, Period 2.</span>

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