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2 years ago

What kind of solid often has the highest melting points?

Chemistry

2 answers:

ki77a [65]2 years ago

7 0

Solids made of atoms

Explanation: Apex

vovikov84 [41]2 years ago

6 0

Answer:

ones with ionic bonds

Explanation:

they have high melting and boiling points

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What is formed when 2 non metals reacts?

ryzh [129]

Answer:

A) covalent bond

Explanation:

Covalent bonding generally happens between nonmetals.

4 0

3 years ago

Given the following at 25C calculate delta Hf for HCN (g) at 25C. 2NH3 (g) +3O2 (g) + 2CH4 (g) ---> 2HCN (g) + 6H2O (g) delta

AysviL [449]

Answer: The $\Delta H_f$ for HCN (g) in the reaction is 135.1 kJ/mol.

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. The equation used to calculate enthalpy change is of a reaction is:

$\Delta H_{rxn}=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]$

For the given chemical reaction:

$2NH_3(g)+3O_2(g)+2CH_4(g)\rightarrow 2HCN(g)+6H_2O(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H_{rxn}=[(2\times \Delta H_f_{(HCN)})+(6\times \Delta H_f_{(H_2O)})]-[(2\times \Delta H_f_{(NH_3)})+(3\times \Delta H_f_{(O_2)})+(2\times \Delta H_f_{(CH_4)})]$

We are given:

$\Delta H_f_{(H_2O)}=-241.8kJ/mol\\\Delta H_f_{(NH_3)}=-80.3kJ/mol\\\Delta H_f_{(CH_4)}=-74.6kJ/mol\\\Delta H_f_{(O_2)}=0kJ/mol\\\Delta H_{rxn}=-870.8kJ$

Putting values in above equation, we get:

$-870.8=[(2\times \Delta H_f_{(HCN)})+(6\times (-241.8))]-[(2\times (-80.3))+(3\times (0))+(2\times (-74.6))]\\\\\Delta H_f_{(HCN)}=135.1kJ$

Hence, the $\Delta H_f$ for HCN (g) in the reaction is 135.1 kJ/mol.

8 0

3 years ago

How do producers and consumers get energy from the sun?

Marysya12 [62]

Answer: In photosynthesis, producers combine carbon dioxide, water, and sunlight to produce oxygen and sugar (their food). Other organisms get energy by eating producers. ... It cannot directly use the Sun's energy to make food. As a consumer, it has to eat— or, consume— other organisms for energy.

Explanation: Thats how both producers and consumers get energy

6 0

3 years ago

Can someone please help me? i will give brainlist

MA_775_DIABLO [31]

Answer:

B. Design homes that can be built on stilts where flooding is likely to occur.

C. Replace power lines that have been damaged by severe weather.

Explanation:

$Hope$ $this$ $helps!$ $:)$

5 0

1 year ago

. how many lone pairs of electrons are present in the lewis structure of calcium sulfide?

miv72 [106K]

Answer:
Four

Explanation:
Calcium Sulfide is an ionic compound made up of Ca²⁺ and S²⁻.
Ca²⁺ is formed as,

Ca → Ca²⁺ + 2 e⁻

These two electrons are accepte by Sulfur as,

S + 2 e⁻ → S²⁻

So, before accepting 2 electrons S was having six valence electrons, after accepting two electrons from Ca it has 8 electrons which are present in four pairs as shown below,

7 0

3 years ago