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4 years ago

Do you round when dividing significant figures

Chemistry

1 answer:

Tatiana [17]4 years ago

4 0

Answer: You multiply and divide when rounding division significant figures

Explanation: Both multiplying and dividing significant figures have the same rule. That rule is, the FINAL ANSWER of a multiplication and division problem should be rounded to the number of significant figures that is the least amount of any figures used in the multiplication or division. Let us demonstrate below.

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The balanced equation for the reaction of aqueous Pb(ClO3)2 with aqueous NaI is Pb(ClO3)2(aq)+2NaI(aq)⟶PbI2(s)+2NaClO3(aq) What

ryzh [129]

Answer : The mass of $PbI_2$ precipitate produced will be, 9.681 grams.

Explanation : Given,

Molarity of NaI = 0.210 M

Volume of solution = 0.2 L

Molar mass of $PbI_2$ = 461.01 g/mole

First we have to calculate the moles of $NaI$ .

$\text{Moles of }NaI=\text{Molarity of }NaI\times \text{Volume of solution}=0.210M\times 0.2L=0.042moles$

Now we have to calculate the moles of $PbI_2$ .

The balanced chemical reaction is,

$Pb(ClO_3)_2(aq)+2NaI(aq)\rightarrow PbI_2(s)+2NaClO_3(aq)$

From the balanced reaction we conclude that

As, 2 moles of $NaI$ react to give 1 mole of $PbI_2$

So, 0.042 moles of $NaI$ react to give $\frac{0.042}{2}=0.021$ moles of $PbI_2$

Now we have to calculate the mass of $PbI_2$ .

$\text{Mass of }PbI_2=\text{Moles of }PbI_2\times \text{Molar mass of }PbI_2$

$\text{Mass of }PbI_2=(0.021mole)\times (461.01g/mole)=9.681g$

Therefore, the mass of $PbI_2$ precipitate produced will be, 9.681 grams.

6 0

4 years ago

In science, we like to develop explanations that we can use to predict the outcome of events and phenomena. Try to develop an ex

Kay [80]

The question is incomplete. The complete question is :

In science, we like to develop explanations that we can use to predict the outcome of events and phenomena. Try to develop an explanation that tells how much NaOH needs to be added to a beaker of HCl to cause the color to change. Your explanation can be something like: The color change will occur when [some amount] of NaOH is added because the color change occurs when [some condition]. The goal for your explanation is that it describes the outcome of this example, but can also be used to predict the outcome of other examples of this phenomenon. Here's an example explanation: The color of the solution will change when 40 ml of NaOH is added to a beaker of HCl because the color always changes when 40ml of base is added. Although this explanation works for this example, it probably won't work in examples where the flask contains a different amount of HCl, such as 30ml. Try to make an explanation that accurately predicts the outcome of other versions of this phenomenon.

Solution :

Consider the equation of the reaction between NaOH and $HCl$

NaOH (aq) + HCl (aq) → NaCl(aq) + $H_2O (l)$

The above equation tells us that $1 \text{mole}$ of $NaOH$ reacts with $1 \text{mole}$ of $HCl$ .

So at the equivalence point, the moles of NaOH added = moles of $HCl$ present.

If the volume of the $HCl$ taken = $V_1$ mL and the conc. of $HCl$ = $M_1$ mole/L

The volume of NaOH added up to the color change = $V_2 \text{ and conc of NaOH = M}_2$ mole/L

Moles of $HCl$ taken = $V_1 \ mL \times M_1 \ mol/100 \ mL = V_2M_2 \times 10^{-3}$ moles.

The color change will occur when the moles of NaOH added is equal to the moles of $HCl$ taken.

Thus when $V_1 M_1 \times 10^{-3} = V_2M_2 \times 10^{-3}$

or when $V_1M_1 = V_2M_2$

or $V_2=\frac{V_1M_1}{M_2}$ mL of NaOH added, we observe the color change.

Where $V_1, M_1$ are the volume and molarity of the $HCl$ taken.

$M_2$ is the molarity of NaOH added.

When both the NaOH and $HCl$ are of the same concentrations, i.e. if $M_1=M_2$ , then $V_2=V_1$

Or the 40 mL of $HCl$ will need 40 mL of NaOH for a color change and

30 mL of $HCl$ would need 30 mL of NaOH for the color change (provided the concentration $M_1=M_2$ )

7 0

3 years ago

Which phenomenon best explains the miscibility of heptane (CH3CH2CH2CH2CH2CH2CH3) in pentane (CH3CH2CH2CH2CH3)

Nuetrik [128]

The phenomenon that best explains the miscibility of heptane in pentane is that both are non-polar compounds.

<h3>Solubility of compounds</h3>

Solubility is defined as the ability of a solute or substance to dissolve in a given solvent and at a particular temperature.

Heptane is a straight-chain alkane hydrocarbon that contains 7 carbon atoms. It is a non polar solvent.

Pentane is also a straight-chain alkane hydrocarbon that contains 5 carbon atoms. It is also a non- polar solvent.

Both pentane and heptane are non-polar because the atoms in their molecules share electrons equally. They are able to dissolve each other because they are alike.

Learn more about solubility here:

brainly.com/question/23946616

6 0

2 years ago

What’s potassium+calcium sulphate

Dvinal [7]

Potassium +calcium sulphate ------> K2SO4+Ca

5 0

3 years ago

We drop a cube of ice into a glass of water. The mass of the cube of ice is 33.1 g and its initial temperature is −10.2∘C. The m

Nastasia [14]

Answer: The final temperature (T) will be;

16.23°c

Explanation: To find the final temperature of any mixture of substance with an initial temperature use the formula;

M1c(T-T1) + M2c(T-T2)=0

c is the specific heat capacity of the two different substance, but because ice and water are the same, we assume c to be 1

T= final temperature of the mixture

T1= initial temperature of the ice= -10.2°c

T2= initial temperature of the water= 19.7°c

M1= mass of ice= 33.1g

M2= mass of water= 251g

Using the formula above

33.1(T-(-10.2)) + 251(T-19.7)=0

Solving out the bracket

33.1T + 337.62 + 251T - 4944.7 = 0

Collecting like terms to both side of the equation and solving

33.1T + 251T = 4944.7 - 33.62

284.1T = 4607.08

T = 4607.08÷284.1 = 16.23°c

6 0

3 years ago