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3 years ago

How does the periodic table arrange element's atomic number?

Chemistry

1 answer:

Dmitry [639]3 years ago

7 0

Answer:

The periodic table of elements arranges all of the known chemical elements in an informative array. Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. The rows are called periods.

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Which of the following happens when a reaction reaches dynamic equilibrium in a closed system?

laiz [17]

Answer: B

Explanation:

At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction, and thus the concentrations of the reactants and products must be constant.

8 0

2 years ago

To measure the amount of nickel in some industrial waste fluid, an analytical chemist adds sodium hydroxide solution to a sample

Cloud [144]

Answer:

The final balanced equation is

Ni2+ + 2NaOH --> Ni (OH)2 + 2Na+

Explanation:

It is given that sodium hydroxide is added to collect the solid nickel(II) hydroxide product

The empirical equation for this statement is

Ni2+ + NaOH --> Ni (OH)2 + Na+

We will first balance the hydroxide molecule. On the right side there are two OH molecules.

Thus, on the left side we will take 2 sodium hydroxide

Ni2+ + 2NaOH --> Ni (OH)2 + Na+

Now we will balance the sodium ion which are 2 in numbers on the left side and 1 on the right side

Ni2+ + 2NaOH --> Ni (OH)2 + 2Na+

So, the final balanced equation is

Ni2+ + 2NaOH --> Ni (OH)2 + 2Na+

8 0

3 years ago

A nuclear reactor core must stay at or below 95 °C to remain in good working condition. Cool water at a temperature of 10 °C is

aliina [53]

Answer:

$\large \boxed{\text{67 000 g}}$

Explanation:

This is a problem in calorimetry — the measurement of the quantities of heat that flow from one object to another.

It is based on the Law of Conservation of Energy — Energy can be transformed from one type to another, but it cannot be destroyed or created.

If heat flows out of the reactor (negative), the same amount of heat must flow into the water (positive).

Since there is no change in total energy,

heat₁ + heat₂ = 0

The symbol for the quantity of heat transferred is q, so we can rewrite the word equation as

q₁ + q₂ = 0

The formula for the heat absorbed or released by an object is

q = mCΔT, where

m = the mass of the sample

C = the specific heat capacity of the sample, and

ΔT = T_f - T_i = the change in temperature

1. Equation

There are two heat flows in this problem,

heat released by reactor + heat absorbed by water = 0

q₁ + q₂ = 0

q₁ + m₂C₂ΔT₂ = 0

2. Data:

q₁ = -23 746 kJ

m₂ = ?; C₂ = 4.184 J°C⁻¹g⁻¹; T_f = 95 °C; T_i = 10 °C

3. Calculations

(a) Convert kilojoules to joules

$q_{1} = -\text{23 746 kJ} \times \dfrac{\text{1000 J}}{\text{1 kJ}} = -\text{23 746 000 J}$

(b) ΔT

ΔT₂ = T_f - T_i = 95 °C - 10 °C = 85 °C

(c) m₂

$\begin{array}{rcl}q_{1} + q_{2} & = & 0\\\text{-23 746 000 J} + m_{2} \times 4.184 \text{ J$^{\circ}$C$^{-1}$g$^{-1}$} \times 85 \, ^{\circ}\text{C} & = & 0\\\text{-23 746 000 J} + 356m_{2} \text{J$\cdot$g}^{-1} & = & 0\\356m_{2} \text{g}^{-1} & = & 23746000\\m_2&=& \dfrac{23746000}{\text{356 g}^{-1}}\\\\ & = & \textbf{67000 g}\\\end{array}\\$