What is the mass in grams of 2.5 moles of Al?

When 21.45 g of KNO3 was dissolved in water in a calorimeter, the temperature fell from 25.00°C to 14.14 °C. If the heat capacit

pashok25 [27]

25.9 kJ/mol. (3 sig. fig. as in the heat capacity.)

<h3>Explanation</h3>

The process:

$\text{KNO}_3\;(s) \to \text{KNO}_3\;(aq)$ .

How many moles of this process?

Relative atomic mass from a modern periodic table:

K: 39.098;
N: 14.007;
O: 15.999.

Molar mass of $\text{KNO}_3$ :

$M(\text{KNO}_3) = 39.098 + 14.007 + 3\times 15.999 = 101.102\;\text{g}\cdot\text{mol}^{-1}$ .

Number of moles of the process = Number of moles of $\text{KNO}_3$ dissolved:

$\displaystyle n = \frac{m}{M} = \frac{21.45}{101.102} = 0.212162\;\text{mol}$ .

What's the enthalpy change of this process?

$Q = C\cdot \Delta T = 0.505 \times (25.00 - 14.14) = 5.4843\;\text{kJ}$ for $0.212162\;\text{mol}$ . By convention, the enthalpy change $\Delta H$ measures the energy change for each mole of a process.

$\displaystyle \Delta H = \frac{Q}{n} = \frac{5.4843\text{kJ}}{0.212162\;\text{mol}} = 25.8\;\text{kJ}\cdot\text{mol}^{-1}$ .

The heat capacity is the least accurate number in these calculation. It comes with three significant figures. As a result, round the final result to three significant figures. However, make sure you keep at least one additional figure to minimize the risk of rounding errors during the calculation.

4 0

2 years ago

national defense, currency, post office, foreign affairs, & interstate commerce. b. charter local governments, education, pu

katen-ka-za [31]

Answer And Explanation:

Option C is correct.

Lend and borrow money, taxation, law enforcement, charter banks and transportation.

Some of the powers that were mentioned in the other options that weren't concurrent powers (that is, they belong to either the state government alone or the federal government alone) & disqualified them from being the answer include:

National defence (federal), Currency (federal), foreign affairs (federal), intrastate commerce (state) etc.

3 0

3 years ago

When 1 mol of KBr(s) decomposes to its elements, 394 kJ of heat is absorbed. (a) Write a balanced thermochemical equation.

VladimirAG [237]

The balanced thermochemical equation is

KBr ------- K + 1/2 Br2

<h3>What is thermochemical equation? </h3>

A Thermochemical Equation is defined as the balanced stoichiometric chemical equation which includes the enthalpy change, ΔH.

The chemical equation for the decomposition of potassium bromide to its constituent elements bromine ans potassium :

KBr ----- K + Br2

The balanced thermochemical equation of the decomposition of potassium bromide to its constituent elements potassium and bromide as follows

KBr ------- K + 1/2 Br2

As the heat is absorbed in this reaction therefore, heat is positive.

Thus, we concluded that the balanced thermochemical equation is

KBr ------- K + 1/2 Br2

learn more about thermochemical equation:

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8 0

1 year ago

A nitrogen atom has five valence electrons. The Lewis structure shows how a nitrogen atom bonds with three hydrogen atoms to for

nordsb [41]

It has too be 6 or 4