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3 years ago

Which of the following statements BEST describes a compound?

Chemistry

1 answer:

Oliga [24]3 years ago

8 0

Answer:

A compond is made up of 2 or more elements that are both DIFFERENT so the answer is B.

Explanation:

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Explain how changing the concentration The enthalpy change for the reaction, 3CO (g) 2Fe2O3 (s) Imported Asset Fe(s) 3CO2 (g), c

ycow [4]

Answer: For the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as $\Delta H^o$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f(product)]-\sum [n\times \Delta H^o_f(reactant)]$

For the given chemical reaction:

$3CO(g)+2Fe_2O_3(s)\rightarrow Fe(s)+3CO_2(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(Fe(s))})+(3\times \Delta H^o_f_{(CO_2(g))})]-[(3\times \Delta H^o_f_{(CO(g))})+(2\times \Delta H^o_f_{(Fe_2O_3(s))})]$

The enthalpy of formation for the substances present in their elemental state is taken as 0.

Here, iron is present in its elemental state which is solid.

Hence, for the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.

7 0

3 years ago

Where are calcium ions (Ca2+) stored in the body?

ANTONII [103]

Calcium is stored in bones in the body

5 0

2 years ago

Read 2 more answers

What is the percent mass of C8H10 when 123 g of C8H10 dissolved in 765 g of C6H6? Express your answer to three significant figur

3241004551 [841]

Answer:

13.8%

Explanation:

take the 123g and divide it by the total mass which is 123g + 765g

123/888 = .138

multiply by 100 for a percentage = 13.8%

3 0

3 years ago

Start with 3 breads and 2 cheeses. How many products are made? 1 What are the leftovers?

Tanya [424]

Answer:

1 product is made. The left overs are 1 piece of bread and 1 slice of cheese

Explanation:

8 0

2 years ago

Need help on some homework questions I’m stuck on about molarity and dilutions:

Flura [38]

question 1

The moles of C12H22O11 that are in 7.5 L of a 5.8 M C12H22O11 solution is 43.5 moles

calculation

moles = molarity x volume

volume = 7.5 L

molarity = 5.8 M or 5.8 mol/l

moles is therefore = 7.5 l x 5.8 mol/l = 43.5 moles

question 2

% percent =( mas of the solute/ mass of the solution) x 100

mass of solute= ?

mass of the solution = 375 g

% mass = 85 % = 85/100

let the mass of solute be represented by Y

therefore y/375 = 85/100

y=(375 x 85)/100 = 318.75 g

moles = mass/molar mass

= 318.75 g/ 42.4= 7.52 moles

Question 3

The grams of copper metal is 857.25 g

calculate the moles HCl

= molarity x volume = 4.50 L x 6 .00 mol/l= 27 moles

By use of mole ratio of Cu: HCl which is 1:2 the moles of Cu = 27/2 =13.5 moles

mass = moles x molar mass

= 13.5 moles x 63.5 g/mol = 857.25 g

question 4

Complete description of how to make 3.5 L of 2.0 M NaCl solution from a stock of 6.0 M NaCl is that measure 1.17 L of 6.0 M NaCl, Dissolve it to 3.5 L to make 2.0 M NaCl

calculation

M1V1 = M2V2

m1= 2.0 M

V1=3.5 L

M2= 6.0 M

V2=?

v2 = M1V1/M2

= (3.5 L x 2.0 M)/ 6.0 M= 1.17 L

explanation : measure 1.17 L of 6.0M NaCl and then dissolve it to 3.5 L to make 2.0 M NaCl

question 5

The number of grams of stock solution that is in 90.0 % is HCl by mass that would be needed to make 175 g is 77.78 grams

calculation

This is calculated using M1C1= M2C2 formula

M1 = ?g

C1 =90.0%

M1= 175 g

C1= 40.0 %

make M1 the subject of the formula

M1= M2C2/C1

M1 is therefore =( 175 g x 40) / 90 = 77.78 g

Question 6

The grams of silver metal is 127 g

% mass = mass of solute/ mass of solution

% mass = 80% = 80/100

mass of solute (AgNO3)= ?

mass of solution = 250 g

let the mass of solute be represented by Y

therefore Y/ 250 = 80/100

Y= (250 x 80) /100 =200 g of AgNO3

moles = mass/molar mass

moles of AgNO3 = 200 g/ 169.87 g/mol =1.178 moles

The mole ratio of AgNO3: Ag is 2:2=1:1 therefore the moles of Ag= 1.178 moles

mass= moles x molar mass

= 1.178 moles x 107.87 g/mol =127.07 g

6 0

3 years ago