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3 years ago

suggest one reason why 1g of cobalt oxide nanoparticles is a better catalyst than 1g of cobalt oxide powder

1 answer:

7 0

Particles are smaller, a reactant would be exposed to more cobalt atoms. Causing the reaction to happen quicker than with larger particles.

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An object has a mass of 45.0 g and a volume of 4.0 ml. what is its density?

andreev551 [17]

Answer:

The answer is

Explanation:

The density of a substance can be found by using the formula

$Density = \frac{mass}{volume}$

From the question

mass = 45 g

volume = 4 mL

Substitute the values into the above formula and solve for the density

We have

$Density = \frac{45}{4}$

We have the final answer as

Hope this helps you

4 0

3 years ago

A human red blood cell is about 0.000008 meters in diameter which of the following represents this number in scientific notation

lukranit [14]

<u>Given:</u>

Diameter of a red blood cell = 0.000008

<u>To determine:</u>

The scientific notation corresponding to the given number

<u>Explanation:</u>

Scientific notation is a concise way of representing a very large or small number. It is written in two parts:

Given Number = Digits * Power of 10

In this case we have:

0.000008 = 8.0 * 10⁻⁶

3 0

3 years ago

The The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k=0.029 W/ m measured temperature differ

vfiekz [6]

Answer:

Heat flux = 13.92 W/m2

Rate of heat transfer throug the 3m x 3m sheet = 125.28 W

The thermal resistance of the 3x3m sheet is 0.0958 K/W

Explanation:

The rate of heat transfer through a 3m x 3m sheet of insulation can be calculated as:

$q=-k*A*\frac{\Delta T}{\Delta X}\\\\q=-0.029\frac{W}{m*K}*(3m*3m)*\frac{12K}{0.025m} =125.28W$

The heat flux can be defined as the amount of heat flow by unit of area.

Using the previous calculation, we can estimate the heat flux:

$heat \, flux=\frac{q}{A}=\frac{125.28 W}{9 m^{2} } =13.92 W/m^{2}$

It can also be calculated as:

$q/A=-k*\frac{\Delta T}{\Delta X}$

The thermal resistance can be expressed as

$\Delta T=R_t*Q\\R_t=\Delta T/Q=\frac{\Delta X}{k*A}$

For the 3m x 3m sheet, the thermal resistance is

$R_t = \frac{\Delta X}{k*A}=\frac{0.025m}{0.029W/mK*9m^{2}}=0.0958 \, K/W$

4 0

3 years ago

What is the pH of a KOH solution that has [H ] = 1. 87 × 10–13 M? What is the pOH of a KOH solution that has [OH− ] = 5. 81 × 10

vlada-n [284]

pH is the hydrogen ion concentration and pOH is the hydroxide ion concentration in the solution. pH KOH is 12.73, pOH KOH is 2.24 and pH NaCl is 7.

pH is the negative log of the hydrogen ion concentration and pOH is the negative log of the hydroxide ion concentration.

The relation between the pH and pOH can be given as, $\rm pOH = 14 - pH$

The pH of KOH can be calculated by the formula,

$\rm pH = \rm -log [H^{+}]$

In the first case, the concentration of the KOH is $1. 87 \times 10^{-13}\;\rm M$

Substituting values in the equation:

$\begin{aligned} \rm pH &= \rm -log [H^{+}]\\\\&= \rm -log [1. 87 \times 10^{-13}\;\rm M ]\\\\&= 12.73\end{aligned}$

Hence, the pH of KOH is 12.73.

<u />

pOH of KOH can be calculated by the formula,

$\rm pOH = \rm -log [OH^{-}]$

The hydroxide concentration of the KOH solution is $5. 81 \times 10^{-3}\;\rm M$

Substituting value in the equation:

$\begin{aligned} \rm pOH &= \rm -log [OH^{-}]\\\\&= \rm -log [5. 81 \times 10^{-3}\;\rm M ]\\\\&= 2.24 \end{aligned}$

Hence, the pOH of KOH is 2.24

<u />

The pH of NaCl can be calculated by the formula,

$\rm pH = \rm -log [H^{+}]$

In the third case, the concentration of the NaCl is $1. 00\times 10^{-7}\;\rm M$

Substituting values in the equation:

$\begin{aligned} \rm pH &= \rm -log [H^{+}]\\\\&= \rm -log [1. 00 \times 10^{-7}\;\rm M ]\\\\&= 7 \end{aligned}$

Hence, the pH of KOH is 7.0.

Therefore, KOH is basic and NaCl is approximately neutral.

Learn more about pH and pOH here:

brainly.com/question/13885794

3 0

2 years ago

The coefficients in the balanced chemical equation are used to determine mole ratios.

padilas [110]

Answer:

1 mole of HCl or NaOH gives you 1 mole of H2O , then the number of moles in H2O is: [ 1÷1×1 ] = 1 mole.

Explanation:

6 0

2 years ago