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3 years ago

The first attempt to classify the elements was made by newlands true or false

Chemistry

1 answer:

Keith_Richards [23]3 years ago

8 0

Answer:

True. An English scientist by the name of John Newlands tried to classify the elements in a unique manner. He first started by arranging all the elements in a ascending order according to their atomic weights.

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A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the

baherus [9]

Answer: 1. $9.08\times 10^{-6}$ moles

2. 90 mg

Explanation:

$O_3(g)+2NaI(aq)+H_2O(l) \rightarrow O_2(g)+I_2(s)+2NaOH(aq)$

According to stoichiometry:

1 mole of ozone is removed by 2 moles of sodium iodide.

Thus $4.54 \times 10^{-6}$ moles of ozone is removed by = $\frac{2}{1}\times 4.54 \times 10^{-6}=9.08\times 10^{-6}$ moles of sodium iodide.

Thus $9.08\times 10^{-6}$ moles of sodium iodide are needed to remove $4.54\times 10^{-6}$ moles of $O_3$

2. $\text{Number of moles of ozone}=\frac{0.01331g}{48g/mol}=0.0003moles$

According to stoichiometry:

1 mole of ozone is removed by 2 moles of sodium iodide.

Thus 0.0003 moles of ozone is removed by = $\frac{2}{1}\times 0.0003=0.0006$ moles of sodium iodide.

Mass of sodium iodide= $moles\times {\text {molar mass}}=0.0006\times 150g/mol=0.09g=90mg$ (1g=1000mg)

Thus 90 mg of sodium iodide are needed to remove 13.31 mg of $O_3$ .

3 0

3 years ago

State whether the following statements are true or false. If false, explain why. (a) A reaction stops when equilibrium is reache

Elden [556K]

Answer:

(a) False;

(b) False;

(c) False;

(d) True.

Explanation:

(a) When equilibrium is reached, the forward reaction rate becomes equal to the reverse reaction rate, that's why the molarity of each species remains constant, but reactions don't stop.

(b) According to the principle of Le Chatelier, an increase in molarity of either reactants or products would lead to a disturbance of equilibrium. This disturbance would lead to the shift of equilibrium towards the side which would minimize such a disturbance.

(c) Equilibrium constant is only temperature-dependent, it's independent of molarity, pressure, volume etc. of any species present in the reaction.

(d) The greater the initial molarity of reactants, the more products can be formed, e. g., since the ratio of products to reactants should be kept constant, the larger the amount of reactants, the greater the amount of products formed to keep a constant ratio.

7 0

3 years ago

How many moles are in 20g of potassium (K)?

otez555 [7]

Explanation:

Hi for this one u just need to remember and use the equation.

$moles = \frac{mass}{mr}$

then u find mr of potassium which is 39.1.

then u do

$\frac{20}{39.1}$

you get the answer as 0.5115 write ur answer to 3 significant figures which will be 0.512 moles .

hope this helps :)

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3 years ago

Classify each item by matching as organic

Aloiza [94]

<span>Table salt is inorganic TNT is organic Glucose is organic 2,4-D is organic Limestone is inorganic Water is inorganic What makes a compound organic is the presence of a carbon, with the exception of cabonates. In this case all of the compounds in this list that have carbon except for CaCO3, are organic and the other compounds are inorganic.</span>

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3 years ago

Need help on stoichiometry asap please

lbvjy [14]

1. Convert 135g Fe2O3 to moles, divide by 2, and multiply the resulting number by the molar mass of Al

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3 years ago

The first attempt to classify the elements was made by newlands true or false​

The first attempt to classify the elements was made by newlands true or false