A-potassiumB-leadC-ironD-magnesiumE-zinc

Chemistry

1 answer:

viktelen [127]3 years ago

6 0

The unknown substance : Lead

<h3>Further explanation</h3>

Given

Density of element

mass of unknown substance = 40 g

volume = 3.5 cm³

Required

The density of unknown substance

Solution

Density is the ratio of mass per unit volume

The unit of density can be expressed in g/cm³ or kg/m³

Density formula:

$\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}$

Input the value to find the density of an unknown substance :

ρ = 40 g : 3.5 cm³

ρ = 11.43 g/cm³

If we look at the table, the substance which has a density of 11.43 is Lead

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What is the total amount of heat required to completely melt 347 grams of ice at its melting point?

Bogdan [553]

In order to calculate the amount of heat energy required to melt 347 grams of ice, we need to will apply the equation:
Q = ml, where m is the mass of substance and l is its latent heat of fusion. For ice, the latent heat of fusion is 334 joules per gram. Therefore:
Q = 347 x 334
Q = 112,558 joules of energy

Hope this helped.

7 0

3 years ago

1. How were matter and energy conserved in each demonstration?

marshall27 [118]

Matter and energy are conserved in nature through their use by biological systems, which is dedicated by the Law of conservation.

<h3>What does matter and energy conservation mean?</h3>

Matter and energy conservation indicate that organisms can not create or destroy these elements in nature.

Matter and energy conservation are fundamental for maintaining the state of equilibrium (homeostasis) of biological systems.

In conclusion, matter and energy are conserved in nature through their use by biological systems, which is dedicated by the Law of conservation.

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8 0

2 years ago

2H2 + O2 → 2H2O

pantera1 [17]

Okay
Mr (H2O)= 18g
therefore moles of H2O
is 720.8/18= 40.04mol
the ratio of H2 to O2 to H2O is
2 : 1 : 2
so moles of H2 is same as H2O here
H2= 40.04moles

moles of O2 is half
so 40.04 x 0.5
20.02moles

grams of O2 is
its moles into Mr of O2
that's 20.02 x 32 = 640.64g

6 0

3 years ago

Manganese (Mn) has many possible oxidation numbers (+2 and +4 are just two of these). Write the correct formulas and names for t

ohaa [14]

Answer:

Oxide of manganese, Potassium permanganate, Manganese bromide and manganese oxide.

Explanation:

1. Manganese dioxide

Its chemical formula is $MnO_2$ . It is +4 oxidation state. It is a black solid which is fairly stable.