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3 years ago

When a substance goes directly from a solid state to a gas state as dry ice does?

Chemistry

2 answers:

Triss [41]3 years ago

6 0

This is called "sublimation", and the intermolecular forces, in this case, would decrease.

love history [14]3 years ago

6 0

Answer:

It's undergoing a phase change

it's called sublimation

the line on the energy-vs.-temperature graph is horizontal.

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How many grams are in 2.3 x 10^ -4 moles of calcium phosphate?

Yanka [14]

Answer:

Mass = 713.4 ×10⁻⁴ g

Explanation:

Given data:

Number of moles of calcium phosphate = 2.3×10⁻⁴ mol

Mass of calcium phosphate = ?

Solution:

Formula:

Number of moles = mass/molar mass

Molar mass of calcium phosphate is 310.18 g/mol

by putting values,

2.3×10⁻⁴ mol = mass / 310.18 g/mol

Mass = 2.3×10⁻⁴ mol × 310.18 g/mol

Mass = 713.4 ×10⁻⁴ g

3 0

3 years ago

Covalent compounds are generally not very hard. Justify the statement.

Eduardwww [97]

Covalent compounds are generally not very hard because they are formed by two or more nonmetallic atoms.

<h3>COVALENT COMPOUNDS:</h3>

Covalent compounds are compounds whose constituent elements are joined together by covalent bonds.

Covalent bonding occurs when two or more nonmetallic atoms of an element share valence electrons. This means that covalent compounds will not be physically hard since they constitute non-metals.

Examples of covalent compounds are:

H2 - hydrogen
H2O - water
HCl - hydrogen chloride
CH4 - methane

Learn more about covalent compounds at: brainly.com/question/21505413

4 0

3 years ago

The relationship between pressure and volume, when moles and temperature of a gas are held constant, is: PV = k. We could say th

pochemuha

You can say that if the volume of the gas is halved, the pressure is doubled.

The expression shows that pressure and volume are inversely proportional if temperature and amount of gas is held constant. This means that if volume goes down the pressure needs to go up. That also means that in order to maintain the K value, if pressure is doubled the volume needs to be halved and if the pressure is halved the volume needs to be doubled.

This relationship only works if we assume everything else (Temperature and moles of gas) to be constant.

7 0

4 years ago

What fraction of a Sr-90 sample remains unchanged after 87.3 years

jolli1 [7]

The answer is 1/8.

Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1. $(1/2)^{n} = x$ ,
where:
n - a number of half-lives
x - a remained fraction of a sample

2. $t_{1/2} = \frac{t}{n}$
where:
 $t_{1/2}$ - half-life
t - total time elapsed
n - a number of half-lives

The half-life of Sr-90 is 28.8 years.
So, we know:
t = 87.3 years
 $t_{1/2}$ = 28.8 years

We need:
n = ?
x = ?

We could first use the second equation, to calculate n:
If:
$t_{1/2} = \frac{t}{n}$ ,
Then:
$n = \frac{t}{ t_{1/2} }$
⇒ $n = \frac{87.3 years}{28.8 years}$
⇒ $n=3.03$
⇒ n ≈ 3

Now we can use the first equation to calculate the remained amount of the sample.
 $(1/2)^{n} = x$
⇒ $x=(1/2)^3$
⇒ $x= \frac{1}{8}$

8 0

4 years ago

A sample of gas has a pressure of 1.8 atm and a volume of 2.5 L, what would be the pressure of this sample of gas if the volume

jek_recluse [69]

Boyle's Law
P1V1 = P2V2
1.8 atm * 2.5 L = P2 * 1.2 L
1.8 atm * 2.5 L / 1.2 L = P2
3.75 atm = P2
Using significant digits, the answer is 3.8 atm

3 0

3 years ago

Read 2 more answers