Question 9(Multiple Choice Worth 1 points)

onsider the following reaction: CaCN2 + 3 H2O → CaCO3 + 2 NH3 105.0 g CaCN2 and 78.0 g H2O are reacted. Assuming 100% efficiency

mestny [16]

Answer : The excess reactant is, $H_2O$

The leftover amount of excess reagent is, 7.2 grams.

Solution : Given,

Mass of $CaCN_2$ = 105.0 g

Mass of $H_2O$ = 78.0 g

Molar mass of $CaCN_2$ = 80.11 g/mole

Molar mass of $H_2O$ = 18 g/mole

Molar mass of $CaCO_3$ = 100.09 g/mole

First we have to calculate the moles of $CaCN_2$ and $H_2O$ .

$\text{ Moles of }CaCN_2=\frac{\text{ Mass of }CaCN_2}{\text{ Molar mass of }CaCN_2}=\frac{105.0g}{80.11g/mole}=1.31moles$

$\text{ Moles of }H_2O=\frac{\text{ Mass of }H_2O}{\text{ Molar mass of }H_2O}=\frac{78.0g}{18g/mole}=4.33moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$CaCN_2+3H_2O\rightarrow CaCO_3+2NH_3$

From the balanced reaction we conclude that

As, 1 mole of $CaCN_2$ react with 3 mole of $H_2O$

So, 1.31 moles of $CaCN_2$ react with $1.31\times 3=3.93$ moles of $H_2O$

From this we conclude that, $H_2O$ is an excess reagent because the given moles are greater than the required moles and $CaCN_2$ is a limiting reagent and it limits the formation of product.

Left moles of excess reactant = 4.33 - 3.93 = 0.4 moles

Now we have to calculate the mass of excess reactant.

$\text{ Mass of excess reactant}=\text{ Moles of excess reactant}\times \text{ Molar mass of excess reactant}(H_2O)$

$\text{ Mass of excess reactant}=(0.4moles)\times (18g/mole)=7.2g$

Thus, the leftover amount of excess reagent is, 7.2 grams.

8 0

3 years ago

Ni (s) + O2 (g) → NiO (s)

kicyunya [14]

Answer:

Explanation:

2NiS + 3O2 = 2NiO + 2SO2

3 0

3 years ago

In the laboratory a student uses a "coffee cup" calorimeter to determine the specific heat of a metal. She heats 19.6 grams of z

storchak [24]

Answer:

The specific heat of zinc is 0.375 J/g°C

Explanation:

<u>Step 1: </u>Data given

Mass of zinc = 19.6 grams

Mass of water = 82.9 grams

Initial temperature of zinc T1= 98.37 °C

Initial temperature of water T1= 24.16 °C

Final temperature of water (and zinc) T2 = 25.70 °C

Specific heat of water = 4.184 J/g°C

<u>Step 2: </u>Calculate Specific heat of zinc

Q=m*c*ΔT

Qzinc = -Qwater

m(zinc)*C(zinc)*ΔT(zinc) = -m(water)*C(water)*ΔT(water)

⇒ with mass of water = 82.9 grams

⇒ with C(water) = 4.184 J/g°C

⇒ with ΔT(water) = T2 - T1 = 25.70 - 24.16 = 1.54

⇒ with mass of zinc = 19.6 grams

⇒ with C(zinc) = TO BE DETERMINED

⇒ with ΔT(zinc) = T2 -T1 = 25.70 - 98.37 = -72.67°C

Qzinc = -Qwater

m(zinc)*c(zinc)* ΔT(zinc) = - m(water)*c(water)* ΔT(water)

19.6g* C(zinc) * (-72.67°C) = - 82.9g* 4.184 J/g°C * 1.54 °C

-1424.332*C(zinc) = -534.155

C(zinc) = 0.375 J/g°C

The specific heat of zinc is 0.375 J/g°C

4 0

3 years ago

What is the result of multiplying (2.5 × 1010) × (3.5 × 10-7)? Use the correct number of significant digits.

kow [346]

the result of multiplying (2.5 × 10¹⁰) and (3.5 × 10⁻⁷) is 8.8.10³ (cause the result must have 2 significant number)

<h3><em>Further Explanation</em> </h3>

Significant numbers are numbers obtained from the measurement results of exact numbers and the last number estimated

In scientific notation, all numbers are displayed before the big order is called significant numbers

the scientific notation can be described as:

a, ... x 10ⁿ

a, ... called an important number

10ⁿ is called a big order

Rules for significant numbers in general:

1. all non-zero numbers are significant numbers

2. a zero which is located between two non-zero numbers including a significant number

3. all zeros are located in the final row written behind the decimal point include significant number

4. zero decimal point is not significant number

In the question it is known that (2.5 × 10¹⁰) and (3.5 × 10⁻⁷) both have a significant number in a row 2.5 and 3.5

so that it meets the rule of significant numbers which is multiplication of 2 significant number produces numbers that have the fewest significant numbers, So the multiplication of the two will produce 2 significant number

So that we do the significant number then proceed a big order

1. Multiplication of significant number2.5 x 3.5 = 8.75

2. a big order multiplication 10¹⁰ x 10⁻⁷ = 10¹⁰⁻⁷ = 10³

So the result = 8.75.10³

Because the result must have 2 significant number , the result is 8.8.10³ (8.75 we round up)

<h3><em> Learn more</em></h3>

significant figures brainly.com/question/11151926

significant figures in the following number: 5.67 x 106 brainly.com/question/7539478

the number of significant figures is 0.025 brainly.com/question/10343704

0.080 significant figures brainly.com/question/1999241

the fewest number of significant figures brainly.com/question/11464470

5 0

3 years ago

Read 2 more answers

Select the correct answer.

erastova [34]

Scientific law

Explanation:

A scientific law is a term that refers to a fact that naturally occurs in the universe.

Scientific laws are natural laws and they hold true.

Scientific law is a well tested idea that holds through for a range of natural events.
Scientific theories are explanations of phenomenons drawn from series of tests.

Learn more:

experiment brainly.com/question/5096428

#learnwithBrainly

3 0

3 years ago