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victus00 [196]
3 years ago
9

Help please thank you so much ❤️

Chemistry
1 answer:
mart [117]3 years ago
6 0

Answer:

a)0.326

because pb's atomic mass is 207

mol = mass ÷ atomic mass

mol = 67.5 ÷ 207

mol = 0.326...

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A substance with a density of 2.70 g/mL occupies a volume of 21.3 mL. What is the mass of the sample? Report your answer in unit
katen-ka-za [31]
We know the formula of the density:
ρ =\frac{m}{V} ;
So the mass will be equal to:
m = ρ * V = 2.70  * 21.3 = 57,51 g = 57510 mg of substance.
So the answer is 57510.
7 0
3 years ago
A 14.3-cm3 sample of tin has a mass of 0.104 kg.
VladimirAG [237]
This is a true statement if it is density you are looking for... Density problem.....

Density is the ratio of the mass of an object to its volume.
D = m / V
D = 104g / 14.3 cm³ = 7.27 g/cm³ .............. to three significant digits

The conventions for the units of density is that grams per cubic centimeter (g/cm³) are usually used for solids, but will work for anything. Grams per milliliter (g/mL) are usually used for liquids and grams per liter (g/L) are for gases. Therefore, by convention, the units for tin (a solid) should be in grams per cubic centimeter.

Since 1 mL is equivalent to 1 cm³, then the density could be expressed as 7.27 g/mL.

The accepted value for the density of tin is 7.31 g/cm³
7 0
3 years ago
How did scientists find out about atoms before technology?
sasho [114]

Answer:

There are three ways that scientists have proved that these sub-atomic particles exist. They are direct observation, indirect observation or inferred presence and predictions from theory or conjecture. Scientists in the 1800's were able to infer a lot about the sub-atomic world from chemistry.

Explanation:

Hope this helps

6 0
3 years ago
Which type of acetylcholine receptor is present on postganglionic neurons
Sonja [21]

Answer:

Mescarinic and Nicotinic

Explanation:

Postganglionic fibers can be present in both sympathetic and parasympathetic divisions, their main difference resides in how in the sympathetic division the postganglionic fibers are adrenergic and use norepinephrine (noradrenalin) as a neurotransmitter, in the parasympathetic division, on the other hand, fibers are cholinergic and use acetylcholine as a neurotransmitter, the<em> postganglionic neurons of sweat glands release acetylcholine for the activation of muscarinic receptors, another kind of receptor for acetylcholine are nicotinic receptors </em>that act as transmembrane sodium/potassium channels, while muscarinic receptors need to act through intracellular proteins.

I hope you find this informatiou useful and interesting! Good luck!

4 0
3 years ago
Na+CL2=2NACL is the balanced reaction for the formation of table salt. Given 20 grams of Na and 10 grams of Cl2, which reactant
Elina [12.6K]

Excess reactant : Na

NaCl produced : = 16.497 g

<h3>Further explanation</h3>

Given

Reaction(balanced)

2Na + Cl₂⇒ 2NaCl

20 g Na

10 g Cl₂

Required

Excess reactant

NaCl produced

Solution

mol Na(Ar = 23 g/mol) :

= 20 : 23 = 0.87

mol Cl₂(MW=71 g/mol):

= 10 : 71 g/mol = 0.141

mol : coefficient :

Na = 0.87 : 2 = 0.435

Cl₂ = 0.141 : 1 = 0.141

Limiting reactant : Cl₂(smaller ratio)

Excess reactant : Na

Mol NaCl based on mol Cl₂, so mol NaCl :

= 2/1 x mol Cl₂

= 2/1 x 0.141

= 0.282

Mass NaCl :

= 0.282 x 58.5 g/mol

= 16.497 g

4 0
2 years ago
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