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Mila [183]
2 years ago
12

What two elements are used to make a laser pen light?

Chemistry
1 answer:
irina1246 [14]2 years ago
6 0

Answer:

Helium and Neon

Explanation:

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Which is one way that topographic maps are different from other maps?
anzhelika [568]
One way they are different is that they show elevation
5 0
3 years ago
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A chemistry student needs 45.0mL of pentane for an experiment. By consulting the CRC Handbook of Chemistry and Physics, the stud
Masja [62]

The mass of pentane the student should weigh out is

The density of pentane is 0.626 gcm-3

To calculate the mass of pentane following expression is used,

(Density is defined as the mass divide by volume)

Density = mass / volume

mass of pentane = Density of pentane * Volume of pentane

mass of pentane = 0.626 gcm-3 * 45.0 mL

                             = 28.17 g

Here the unit of mass of pentane is g,

However the unit of density is gcm-3 and unit of volume is mL i.e. cm3

Hence,   Mass = gcm-3 * cm3

              Mass = g

The mass of pentane the student should weigh out is 28.17g

Learn more about Density on

brainly.com/question/1354972

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5 0
1 year ago
A solution of sodium hydroxide (NaOH) was standardized against potassium hydrogen phthalate (KHP). A known mass of KHP was titra
Eddi Din [679]

Answer:

See explanation below

Explanation:

In order to calculate this, we need to use the following expression to get the concentration of the base:

MaVa = MbVb (1)

We already know the volume of NaOH used which is 13.4473 mL. We do not have the concentration of KHP, but we can use the moles. We have the mass of KHP which is 0.5053 g and the molecular formula. Let's calculate the molecular mass of KHP:

Atomic weights of the elements to be used:

K = 39.0983 g/mol;  H = 1.0078 g/mol;  C = 12.0107 g/mol;  O = 15.999 g/mol

MM KHP = (1.0078*5) + (39.0983) + (8*12.0107) + (4*15.999) = 204.2189 g/mol

Now, let's calculate the mole of KHP:

moles = 0.5053 / 204.2189 = 0.00247 moles

With the moles, we also know that:

n = M*V (2)

Replacing in (1):

n = MbVb

Now, solving for Mb:

Mb = n/Vb  (3)

Finally, replacing the data:

Mb = 0.00247 / (13.4473/1000)

Mb = 0.184 M

This would be the concentration of NaOH

8 0
3 years ago
How many grams of Ca(OH)2are required to make 1.5 L of a 0.81 M solution?
FrozenT [24]

Answer:

Mass = 90.28 g

Explanation:

Given data:

Mass of Ca(OH)₂ = ?

Volume of solution= 1.5 L

Molarity of solution = 0.81 M

Solution:

First of all we will calculate number of moles.

Molarity = number of moles / volume in L

by putting values,

0.81 M = Number of moles / 1.5 L

Number of moles = 0.81 M × 1.5 L

Number of moles = 1.22 mol

Mass of Ca(OH)₂ in gram:

Mass = number of moles × molar mass

Mass = 1.22 mol × 74.09 g/mol

Mass = 90.28 g

5 0
2 years ago
Chlorofluorocarbons (CFCs) are no longer used as refrigerants because they destroy the ozone layer. Trichlorofluoromethane (CCl₃
Daniel [21]

Answer:

The molar entropy of the evaporation of Trichlorofluoromethan is 83.516 J/molK.

Explanation:

Entropy :It is defined as amount of energy which is unable to do work or the measurement of randomness or disorderedness in a system.

S=\frac{Q}{T(Kelvins)}

Molar heat of molar vaporization of Trichlorofluoromethane = 24.8 kJ/mol

Temperature at which Trichlorofluoromethan boils , T= 296.95 K

The molar entropy of the evaporation of Trichlorofluoromethan :

=\frac{24.8 kJ/mol}{296.95 K}=0.083516 kJ/mol K = 83.516 J/molK

The molar entropy of the evaporation of Trichlorofluoromethan is 83.516 J/molK.

8 0
2 years ago
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