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tensa zangetsu [6.8K]

3 years ago

5

“Least molecular motion, lowest kinetic energy, strongest forces of attention, most dense packaging of molecules”. Which state o

f matter is defined by this description?

1 answer:

SashulF [63]3 years ago

8 0

<h2><em>Solid. Because molecules densely packed it has a high resistance to flow thereby lower kinetic energy. </em></h2>

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How many grams of copper (II) hydroxide can be prepared from 2.4 grams of copper (II) nitrate (Cu(NO3)2 ) and excess sodium hydr

andreyandreev [35.5K]

Answer:

percentage yield = 67%

Explanation:

Mass of Cu(NO₃)₂ = 15.25 g

Mass of NaOH = 12.75 g

Percentage yield = ?

Solution:

Cu(NO₃)₂ + 2NaOH → Cu(OH)₂ + 2NaNO₃

Moles of Cu(NO₃)₂:

Number of moles = mass/ molar mass

Number of moles = 15.25 g /187.56 g/mol

Number of moles = 0.08 mol

Moles of NaOH :

Number of moles = mass/ molar mass

Number of moles = 12.75 g / 40 g/mol

Number of moles = 0.32 mol

Now we will compare the moles of Cu(OH)₂ with NaOH and Cu(NO₃)₂. NaOH : Cu(OH)₂

2 : 1

0.32 : 1/2×0.32 = 0.16 mol

Cu(NO₃)₂ : Cu(OH)₂

1 : 1

0.08 : 0.08

The number of moles produced by Cu(NO₃)₂ are less so it will limiting reactant.

Mass of Cu(OH)₂:

Mass = number of moles × molar mass

Mass = 0.08 mol × 97.6 g/mol

Mass = 7.808 g

Theoretical yield = 7.808 g

Percent yield:

percentage yield = Actual yield/ theoretical yield × 100

percentage yield = 5.23 g/ 7.808 g × 100

percentage yield = 0.67 × 100

percentage yield = 67%

5 0

3 years ago

What is the difference between physical and chemical change?

Vikki [24]

There are several differences between<span> a </span>physical and chemical change<span> in matter or substances. A </span>physical change<span> in a substance doesn't </span>change<span> what the substance is. In a </span>chemical change<span> where there is a </span>chemical<span> reaction, a new substance is formed and energy is either given off or absorbed.</span>

6 0

3 years ago

Read 2 more answers

The valences of metal x,y and z are 1,2 and 3 respectively. What are the formulae of their;a) hydroxides, b) sulphates, c) hydro

Rina8888 [55]

Answer:

See answer below

Explanation:

AS we know that the valence for those metals X, Y, and Z are 1, 2 and 3, we can determine the formula of each compound.

1. Hydroxides.

An hydroxide is formed when an oxyde of a metal reacts with water. When this happens, the general molecular formula is:

Meₐ(OH)ₙ

Where:

a: valence or charge of the hydroxide (Which is -1)

n: valence of the metal.

Following this, the formula for X, Y and Z would be:

XOH

Y(OH)₂

Z(OH)₃

2. Sulphates

Sulphates follow a similar rule of hydroxide in the general molecular formula, but instead of having a charge of -1, it has a charge of -2 so:

Mₐ(SO₄)ₙ

So, following the rule:

X₂SO₄

Y₂(SO₄)₂ ------> YSO₄

Z₂(SO₄)₃

3. Hydrogens

Following the same rule as the previous, hydrogens works with a charge of -1, so:

MₐHₙ

Then:

XH

YH₂

ZH₃

4. Carbonates.

This follows the same rule as sulphates, with the same charge so:

Mₐ(CO₃)ₙ

Then:

X₂CO₃

YCO₃

Z₂(CO₃)₃

5. Nitrates

Follow the same rule as the hydroxides, with the same charge of -1.

Mₐ(NO₃)ₙ

Then:

XNO₃

Y(NO₃)₂

Z(NO₃)₂

6. Phosphates

In the case of phosphates, these have a charge of -3 so:

Mₐ(PO₄)ₙ

Then:

X₃PO₄

Y₃(PO₄)₂

Z₃(PO₄)₃ ----> ZPO₄

Hope this helps

6 0

3 years ago

Calculate the number of moles when 3.00l of a gas at 814 mmhg and 25 °c?

Mariulka [41]

Volume=V=3L
Pressure=P=814mmHg
Temp=T=25°C

So

No of moles=n

$\\ \rm\rightarrowtail PV=nRT$

$\\ \rm\rightarrowtail n=\dfrac{PV}{RT}$

$\\ \rm\rightarrowtail n=\dfrac{814(3)}{25R}$

$\\ \rm\rightarrowtail n=2442/25R$

$\\ \rm\rightarrowtail n=97.7Rmol$

5 0

2 years ago

An isotope undergoes radioactive decay. The new isotope that forms has an atomic number that is 2 less than the original isotope

jeka57 [31]

It is an alpha decay because when this phenomena occurs an atomic nucleus emits an alpha particle (helium nucleus) and consequentially decays into another atom with a mass number that is reduced by four an atomic number that is reduced by 2 two. The helium atom consists of two protons and two neutrons.

Therefore, the answer is <span>alpha decay because alpha particles have two protons and two neutrons</span>

3 0

3 years ago

Read 2 more answers