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3 years ago

What is the most important characteristic in determining an element’s properties?

Chemistry

1 answer:

lozanna [386]3 years ago

4 0

The number of electrons. The valence (outer) shell is particularly important.

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In the world of chemisty, a 'mole is a number of something ... a very lary large number of something.

yulyashka [42]

Just as a dozen is 12 of something, a mole is about 6.02 * 10^23 of something .

5 0

2 years ago

A 125g metal block at a temperature of 93.2 degrees Celsius was immersed in 100g of water at 18.3 degrees Celsius. Given the spe

nikitadnepr [17]

Answer:

$\large \boxed{34.2\, ^{\circ}\text{C}}$

Explanation:

There are two heat transfers involved: the heat lost by the metal block and the heat gained by the water.

According to the Law of Conservation of Energy, energy can neither be destroyed nor created, so the sum of these terms must be zero.

Let the metal be Component 1 and the water be Component 2.

Data:

For the metal:

$m_{1} =\text{125 g; }T_{i} = 93.2 ^{\circ}\text{C; }\\C_{1} = 0.900 \text{ J$^{\circ}$C$^{-1}$g$^{-1}$}$

For the water:

$m_{2} =\text{100 g; }T_{i} = 18.3 ^{\circ}\text{C; }\\C_{2} = 4.184 \text{ J$^{\circ}$C$^{-1}$g$^{-1}$}$

$\begin{array}{rcl}\text{Heat lost by metal + heat gained by water} & = & 0\\q_{1} + q_{2} & = & 0\\m_{1}C_{1}\Delta T_{1} + m_{2}C_{2}\Delta T_{2} & = & 0\\\text{125 g}\times 0.900 \text{ J$^{\circ}$C$^{-1}$g$^{-1}$} \times\Delta T_{1} + \text{100 g} \times 4.184 \text{ J$^{\circ}$C$^{-1}$g$^{-1}$}\Delta \times T_{2} & = & 0\\112.5\Delta T_{1} + 418.4\Delta T_{2} & = & 0\\112.5\Delta T_{1} & = & -418.4\Delta T_{2}\\\Delta T_{1} & = & -3.719\Delta T_{2}\\\end{array}$

$\Delta T_{1} = T_{\text{f}} - 93.2 ^{\circ}\text{C}\\\Delta T_{2} = T_{\text{f}} - 18.3 ^{\circ}\text{C}$

$\begin{array}{rcl}\Delta T_{1} & = & -3.719\Delta T_{2}\\T_{\text{f}} - 93.2 ^{\circ}\text{C} & = & -3.719 (T_{\text{f}} - 18.3 ^{\circ}\text{C})\\T_{\text{f}} - 93.2 ^{\circ}\text{C} & = & -3.719T_{\text{f}} + 68.06 ^{\circ}\text{C}\\4.719T_{\text{f}} & = & 161.3 ^{\circ}\text{C}\\T_{\text{f}} & = & \mathbf{34.2 ^{\circ}}\textbf{C}\\\end{array}\\\text{The final temperature of the block and the water is $\large \boxed{\mathbf{34.2\, ^{\circ}}\textbf{C}}$}$

3 0

3 years ago

If an atom with a mass of 47 amu has 22 neutrons, what atom is it?

LenaWriter [7]

Answer:

Manganese

Explanation:

At Mass - No neutrons = Atomic Number = #protons in nucleus

47 - 22 = 25 => At. No. 25 is Manganese (Mn)

7 0

3 years ago

Quick! <br>I need to know <br>about how<br>old is the <br>earth!?

Salsk061 [2.6K]

Answer:

4.543 billion years old

3 0

3 years ago

How many moles of water can be obtained from the reaction of 4 moles of O2?

Yuliya22 [10]

Answer: 8moles

Explanation:

The reaction below shows the formation of 2 moles of water from 2 moles of hydrogen and 1 mole of oxygen respectively.

2H2(g) + O2 (g) --> 2H2O(l)

So, if 1 mole of O2 produce 2 mole of H2O

4 moles of O2 will produce Z mole of H2O

To get the value of Z, cross multiply

1 x Z = 4 x 2

Z = 8

So, the equation will be 8H2(g) + 4O2 (g) --> 8H2O(l)

Thus, 4 moles of O2 will produce 8moles of H2O .

6 0

3 years ago