Express 4,935,000 using standard scientific notation

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

CaO + H2O -> Ca(OH)2

yawa3891 [41]

The % yield of Ca(OH)₂ : 62.98%

<h3>Further eplanation </h3>

Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated

General formula:

Percent yield = (Actual yield / theoretical yield )x 100%

An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients

Reaction

CaO + H₂O ⇒ Ca(OH)₂

mass CaO= 4.2 g

mol CaO(MW=56,0774 g/mol) :

$\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{4.2}{56,0774 g/mol}\\\\mol=0.075$

mol Ca(OH)₂ based on mol CaO

mol ratio CaO : Ca(OH)₂,= 1 : 1, so mol Ca(OH)₂ = 0.075

mass Ca(OH)₂(MW=74,093 g/mol) ⇒ theoretical

$\tt mass=mol\times MW\\\\mass=0.075\times 74,093 g/mol\\\\mass=5.557~g$

% yield :

$\tt =\dfrac{actual}{theoretical}\times 100\%\\\\=\dfrac{3.5}{5.557}\times 100\%\\\\=62.98\%$

8 0

2 years ago

Which Mixture is Homogeneous?

lana66690 [7]

The correct answer is: [D]: " milk " .
__________________________________________________________
Choice [A]: "soil" is incorrect; since "soil" is "heterogeneous" {composed of many different "ingredients" .].
__________________________________________________________
Same with "Choice [B]: "granola" [composed of many different ingredients—clumps of sweetened oats, raisins, coconuts, etc.].
__________________________________________________________
Same with "Choice [C]: "salad dressing". {Notice how we usually have to "shake the bottle" ? Composed of multiple ingredients, (e.g. oil, vinegar, and spices, or oil and other spices, and more ingredientes).
__________________________________________________________
Choice: [D]: "milk", as a liquid, is a single, well-mixed, uniform, mixture; as such, it is "homogeneous". Note: "homo-" means "same".
__________________________________________________________

4 0

2 years ago

Which word would not make this statement true?

statuscvo [17]

The first step in the two-step process of making a solution is the breakdown of the solute source into Atomic particles
for a solution to break the solute must be dissociated and break into the atomic particles
so correct option is D
hope it helps

6 0

2 years ago

What happens to a magnetic field if the current carrying wire A has three times as many loops but the same current as the curren

PilotLPTM [1.2K]

More the number of turns, more will be the magnetic field produced.

Hence wire A will have magnetic field greater than wire B.

Hope this helps!

5 0

3 years ago

Read 2 more answers