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3 years ago

What is the significant figure of 5,000,000,000,000

Chemistry

2 answers:

sammy [17]3 years ago

6 0

The significant figure is only 1 which is just the number 5. The zeros don't count.

katrin2010 [14]3 years ago

4 0

5 only one 5...... all 5 just one

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A sample of 8.00 g of Mg(OH)2 is added to 24.2 mL of 0.205 M HNO3. How many moles of Mg(OH)2 our present after the reaction is c

kogti [31]

The amount of Mg(OH)2 present after the reaction is complete is 0.136 moles of Mg(OH)2.

The equation of the reaction is;

2HNO3(aq) + Mg(OH)2(aq) -------> Mg(NO3)2(aq) + 2H2O(l)

Number of moles of Mg(OH)2 = 8.00 g/58 g/mol = 0.138 moles

Number of moles of HNO3 = 0.205 M × 24.2 mL/1000 = 0.00496 moles

Given that;

2 moles of HNO3 reacts with 1 mole of Mg(OH)2

0.00496 moles of HNO3 reacts with 0.00496 moles × 1 mole /2 moles = 0.00248 moles of Mg(OH)2

Hence, Mg(OH)2 is the reactant in excess.

The amount of Mg(OH)2 remaining = Amount present - Amount reacted

Hence; 0.138 moles - 0.00248 moles = 0.136 moles of Mg(OH)2

Learn more: brainly.com/question/9743981

6 0

2 years ago

The rate constant for the second-order reaction !s 0. 54 m-1 s-1 at 300°c. how long (in seconds) would 1t take for the concentra

Jlenok [28]

The answer is 3.63. seconds.

Second order reaction is the reaction in which the rate of reaction depends on either the concentration of two reactant species or on the two times the concentration of single reactant species.

What is the integrated rate law for the second-order reaction?

The integrated rate law that relates the concentration, time and rate constant for the second-order reaction is:

$\frac{1}{[A]} =\frac{1}{[A]_{0} } +kt$

Where

$\begin{array}{l}{\rm{[A] - concentration\ of\ reactant\ A\ at\ time\ t}}\\{{\rm{[A]}}_0}{\rm{ - initial\ concentration\ of\ reactant\ A}}\\{\rm{t - time}}\\{\rm{k - rate\ constant}}\end{array}$

Now, in the given question,

k = $0.54 m^{-1}. s^{-1}$

$[NO_{2} ]= 0.62\ M$

$[NO_{2} ]_{0} = 0.28\ M$

Thus, using the rate law, the time is calculated as-

$\frac{1}{0.28\ M} =\frac{1}{0.62\ M } +(0.54 m^{-1}.s^{-1}) t\\\\(0.54 m^{-1}.s^{-1}) t= \frac{1}{0.28\ M} -\frac{1}{0.62\ M } = 1.959 \\\\$

Therefore,

$t =\frac{1.959}{0.54} = 3.63\ seconds$

Hence, the it would take 3.63 seconds for the concentration of $NO_{2}$ to decrease from 0.62 M to 0.28 M if the reaction is second order.

To learn more about second order reaction visit:

brainly.com/question/17217385

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3 0

2 years ago

A 1.897g sample of Mg(HCO3)2 was heated and decomposed. When the sample

svlad2 [7]

1.5 % is the percent yield in the reaction.

Explanation:

Given that:

original mass of the sample used in reaction = 1.897 grams

product formed after decomposition = 1.071 grams

The reaction for the decomposition:

Mg(HCO3)2 (s) ⇒ CO2 (g) + H2O (g) + MgCO2 (s)

It says that 1 mole of Mg(HCO3)2 yielded 1 mole of MgCO2 on decomposition

68.31 grams/mole or 68.31 grams of MgCO2 is formed

percent yield = $\frac{actual yield}{theoretical yield}$ x 100

putting the values in the equation:

percent yield = $\frac{1.071}{68.31}$

= 0.015 x100

PERCENT YIELD = 1.5 %

8 0

3 years ago

What is chemical energy?

-Dominant- [34]

Answer:
I think it’s D
Explanation:
Chemical strength, Chemical compounds have energy contained in their bonds. Chemical energy may be emitted in the form of heat during a chemical reaction, which is known as an exothermic reaction. The body transforms the chemical energy in food into mechanical energy and heat.

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3 years ago

Which part of the cell does this illustration represent?

Svetllana [295]

Answer: Mitochondria. The mitochondria contains cristae.

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3 years ago

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