Use the portion of the periodic table shown below to answer the questions

Chemistry

1 answer:

leva [86]3 years ago

8 0

Answer:

Part 1:sodium

rubidium

Part 2: protons neutrons and electrons are all 12

The number of protons is equal to the no. of neutrons from the electronic arrangement of magnesium and the no. of electrons is got from the atomic no. of magnesium

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What is the molar mass of a gas if 0.281 g of the gas occupies a volume of 125 ml at a temperature 126 °c and a pressure of 777

AleksAgata [21]

Answer : 72.05 g/mol

Explanation : 

Let's assume that the given gas is an ideal gas. Then we can use ideal gas equation,
PV = nRT

Where,
P = Pressure of the gas (Pa)
V = volume of the gas (m³)
n = number of moles (mol)
R = Universal gas constant (8.314 J mol⁻¹ K⁻¹)
T = temperature in Kelvin (K)

The given data for the gas is,
P = 777 torr = 103591 Pa
V = 125 mL = 125 x 10⁻⁶ m³
T = (126 + 273) = 399 K
R = 8.314 J mol⁻¹ K⁻¹
n = ?

By applying the formula,
103591 Pa x 125 x 10⁻⁶ m³ = n x 8.314 J mol⁻¹ K⁻¹ x 399 K
n = 3.90 x 10⁻³ mol

Moles (mol) = mass (g) / molar mass (g/mol)

Mass of the gas = 0.281 g
Moles of the gas = 3.90 x 10⁻³ mol
Hence,
molar mass of the gas = mass / moles
= 0.281 g / 3.90 x 10⁻³ mol
 = 72.05 g/mol

7 0

3 years ago

Read 2 more answers

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:

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