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3 years ago

When may a scientific theory be revised

Chemistry

1 answer:

harina [27]3 years ago

8 0

Answer:

A theory doesn’t change into a scientific law because of new or better evidence.

Explanation:

A theory will always remain a theory, and i law will remain a law. The reason being that theories and laws may differ on account of newfound countervailing evidence. Remember, theories and laws are very different from hypotheses.

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What are the primary colors?

guapka [62]

The primary colors are blue, red, and yellow.

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3 years ago

onsider the following reaction: CaCN2 + 3 H2O → CaCO3 + 2 NH3 105.0 g CaCN2 and 78.0 g H2O are reacted. Assuming 100% efficiency

mestny [16]

Answer : The excess reactant is, $H_2O$

The leftover amount of excess reagent is, 7.2 grams.

Solution : Given,

Mass of $CaCN_2$ = 105.0 g

Mass of $H_2O$ = 78.0 g

Molar mass of $CaCN_2$ = 80.11 g/mole

Molar mass of $H_2O$ = 18 g/mole

Molar mass of $CaCO_3$ = 100.09 g/mole

First we have to calculate the moles of $CaCN_2$ and $H_2O$ .

$\text{ Moles of }CaCN_2=\frac{\text{ Mass of }CaCN_2}{\text{ Molar mass of }CaCN_2}=\frac{105.0g}{80.11g/mole}=1.31moles$

$\text{ Moles of }H_2O=\frac{\text{ Mass of }H_2O}{\text{ Molar mass of }H_2O}=\frac{78.0g}{18g/mole}=4.33moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$CaCN_2+3H_2O\rightarrow CaCO_3+2NH_3$

From the balanced reaction we conclude that

As, 1 mole of $CaCN_2$ react with 3 mole of $H_2O$

So, 1.31 moles of $CaCN_2$ react with $1.31\times 3=3.93$ moles of $H_2O$

From this we conclude that, $H_2O$ is an excess reagent because the given moles are greater than the required moles and $CaCN_2$ is a limiting reagent and it limits the formation of product.

Left moles of excess reactant = 4.33 - 3.93 = 0.4 moles

Now we have to calculate the mass of excess reactant.

$\text{ Mass of excess reactant}=\text{ Moles of excess reactant}\times \text{ Molar mass of excess reactant}(H_2O)$

$\text{ Mass of excess reactant}=(0.4moles)\times (18g/mole)=7.2g$

Thus, the leftover amount of excess reagent is, 7.2 grams.

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3 years ago

1. How do metals and non-metals react with acids? Write and explain the chemical equation for the reaction of magnesium with sul

Nata [24]

Answer:

1. How do metals and non-metals react with acids?

Ans : Non metals does not react with acids while metals react with acids and produce hydrogen gas that burns with a 'pop'sound.

2. Write and explain the chemical equation for the reaction of magnesium with sulphuric acid and aluminium with hydrochloric acid.

Magnesium + sulphuric acid = Hydrogen + salt

Mg(s) + H2SO4 (aq) MgSO 4(aq) +H2 (g)

Aluminium + Hydrochloric acid = Hydrogen + Aluminium chloride

2Al(s)+6HCl(aq)→2AlCl3(aq)+3H2(g)

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3 years ago

Read 2 more answers

The oceanic crust is made primarily from this type of rock. A) basalt B) halite C) granite D) limestone

masya89 [10]

The answer is A. Basalt rock.

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3 years ago

In your own words list the rules for naming hydrocarbons and substituted hydrocarbons. Be detailed in listing all rules includin

Irina18 [472]

Answer :

The basic rules for naming of hydrocarbons are :

First select the longest possible carbon chain.

The longest possible carbon chain should include the carbons of double or triple bonds.

The naming of alkane is done by adding the suffix -ane, alkene by adding the suffix -ene, alkyne by adding the suffix -yne.

The numbering is done in such a way that first carbon of double or triple bond gets the lowest number.

The carbon atoms of the double or triple bond get the preference over the other substituents present in the parent chain.

If two or more similar alkyl groups are present in a compound, the prefixes di-, tri-, tetra- and so on are used to specify the number of times of the alkyl groups in the chain.

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3 years ago