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4 years ago

A hydrogen atom contains 1 proton, 1 electron, and 0 neutrons. the atomic number of hydrogen is _____. (enter a numeral.

1 answer:

4 0

The atomic number represents the number of protons present in the nucleus of a certain atom. For a hydrogen atom, which has 1 proton, 1 electron, and 0 neutrons, the atomic number of hydrogen would be 1. The atomic number is the same as the charge number of a nucleus. This number is unique for every element in the periodic table and it distinguishes an element. In a neutral atom, this number is equal to the number of electrons in the atom. Also, the atomic number of an element determines the position of the element in the periodic table which for hydrogen, it is the very first element in the periodic table.

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What is the name of the society that scientist form to bring about use one universal system of measurements? (Please hurry)

Katarina [22]

The International Bureau of Weights and Measures is the society that scientist form to bring about one universal system of measurements.

<u>Explanation:</u>

Every theoretical assumptions should be proved experimentally and for that we need a specific system to measure or quantify parameters used in those experiments or the outcome results variables.

The measurements of length should be done by measuring them in meters only and not by liters. The physical properties of every materials should have a particular way of measuring them and this is decided by the International Bureau of Weights and Measures.

They also decide the units of each measurements and the standardization of each units and weights are also done by this society.

6 0

3 years ago

If 42.7 of 0.208 M hydrochloric acid are needed to completely neutralize a solution of calcium hydroxide, how many grams of calc

Montano1993 [528]

Answer:

0.329 g

Explanation:

In the context of this problem, we have a chemical reaction between hydrochloric acid and calcium hydroxide. HCl is the acid here and calcium hydroxide is the base. Hence, we have an acid-base reaction, also known as neutralization reaction.

In a neutralization reaction, water is produced as a product, as well as a salt that we obtain after we exchange the cations: calcium bonds to chloride and hydrogen bonds to hydroxide (the latter is the formation of water). This means we also produce calcium chloride as a product. The overall reaction represents this as:

$Ca(OH)_2(aq)+2 HCl (aq)\rightarrow CaCl_2 (aq)+2 H_2O (l)$

Firslt of all, we wish to find the number of moles of HCl present. Having molarity and volume, this is done by applying the molarity formula. It states that molarity is equal to the rate between moles and volume:

$c_{HCl}=\frac{n_{HCl}}{V_{HCl}}$

Rearranging for moles of HCl, n:

$n_{HCl}=c_{HCl}V_{HCl}$

Based on stoichiometry of the balanced chemical equation, notice that 1 mole of calcium hydroxide reacts with 2 moles of HCl, meaning:

$n_{Ca(OH)_2}=\frac{1}{2} n_{HCl}=\frac{1}{2}c_{HCl}V_{HCl}$

Now that we have the expression for moles, we may also express moles of calcium hydroxide as the ratio between its mass and molar mass:

$n_{Ca(OH)_2}=\frac{m_{Ca(OH)_2}}{M_{Ca(OH)_2}}$

Using the last two equations, we see that:

$\frac{1}{2}c_{HCl}V_{HCl}=\frac{m_{Ca(OH)_2}}{M_{Ca(OH)_2}}\\\therefore m_{Ca(OH)_2}=\frac{1}{2}c_{HCl}V_{HCl}M_{Ca(OH)_2}$

Substitute the given data, as well as the molar mass of calcium hydroxide:

$m_{Ca(OH)_2}=\frac{1}{2}\cdot0.208 M\cdot0.0427 L\cdot74.093 g/mol=0.329 g$

8 0

4 years ago

Which statement best describes a true solution?

kari74 [83]

Option C: a true solution will not separate in a centrifuge.

A solution is said to be a true solution if the solute particles form homogeneous mixture with the solvent. In a homogeneous mixture, the size of the particle of solute is less than 1 nm, can not be seen from naked ice. In such solutions, the solute particles completely dissolves in solvent in all proportions and cannot settle down at bottom if kept at rest for some time.

As complete dissolution of solute takes place, there is no cloudy appearance in the true solution also, once the solution is formed solute and solvent particles can not be separated with simple processes such as heating, boiling and centrifugation.

For example, solution of sugar and water, sugar particles completely dissolve in water to form homogeneous mixture or true solution.

Therefore, a true solution will not separate in a centrifuge.

6 0

3 years ago

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A student uses red litmus paper to test the pH value of different solutions. Which would result in a color change of the litmus

OverLord2011 [107]

The answer is all of the above but fertilizer

5 0

4 years ago

Read 2 more answers

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