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oksano4ka [1.4K]
2 years ago
5

Classify each of the following as either a physical change or a chemical change:

Chemistry
2 answers:
Nady [450]2 years ago
7 0
A and B are both physical changes. The paper is still paper and the wax is still wax. C and D are both chemical changes. You are changing the log when you burn it. It is no longer a log after it is burned completely and the milk cannot be good after it has went sour. It can’t be changed back.
Taya2010 [7]2 years ago
3 0

Answer:

physical change

a b c

chemical change

d

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What mass of KNO3 would be needed to produce 18.4 liters of oxygen gas, measured at 1.50 x 10^3 kPa and 15 degrees Celsius?
Brut [27]

Answer:-

2328.454 grams

Explanation:-

Volume V = 18.4 litres

Temperature T = 15 C + 273 = 288 K

Pressure P = 1.5 x 10^ 3 KPa

We know universal Gas constant R = 8.314 L KPa K-1 mol-1

Using the relation PV = nRT

Number of moles of oxygen gas n = PV / RT

Plugging in the values

n = (1.5 x 10^3 KPa ) x ( 18.4 litres ) / ( 8.314 L KPa K-1 mol-1 x 288 K)

n = 11.527 mol

Now the balanced chemical equation for this reaction is

2KNO3 --> 2KNO2 + O2

From the equation we can see that

1 mol of O2 is produced from 2 mol of KNO3.

∴ 11.527 mol of O2 is produced from 2 x 11.527 mol of KNO3.

= 23.054 mol of KNO3

Molar mass of KNO3 = 39 x 1 + 14 x 1 + 16 x 3 = 101 grams / mol

Mass of KNO3 = 23.054 mol x 101 gram / mol

= 2328.454 grams

7 0
3 years ago
Hydrates are formed with _______ compounds
Triss [41]

Answer:

ionic compounds

Explanation:

7 0
3 years ago
Be sure to answer all parts. Carbon dioxide (CO2) is the gas that is mainly responsible for global warming (the greenhouse effec
Elena L [17]

Answer:

1.60x10⁶ billions of g of CO₂

Explanation:

Let's calculate the production of CO₂ by a single human in a day. The molar mass of glucose is 180.156 g/mol and CO₂ is 44.01 g/mol. By the stoichiometry of the reaction:

1 mol of C₆H₁₂O₆ -------------------------- 6 moles of CO₂

Transforming for mass multiplying the number of moles by the molar mass:

180.156 g of C₆H₁₂O₆ ----------------- 264.06 g of CO₂

4.59x10² g ---------------- x

By a simple direct three rule:

180.156x = 121203.54

x = 672.77 g of CO₂ per day per human

So, in a year, 6.50 billion of human produce:

672.77 * 365 * 6.50 billion = 1.60x10⁶ billions of g of CO₂

5 0
2 years ago
Which part of a feedback mechanism causes change to make up for the departure from the set point? A. sensor B. effector C. respo
koban [17]
I would have to say C. Response.
5 0
3 years ago
Read 2 more answers
Which statement is true?
AleksandrR [38]

Exothermic reaction is where there is release of energy during a reaction

The enthalpy of exothermic reaction is negative

The relation between energy of products, reactants and enthalpy of reaction is

Enthalpy of reaction =  sum of enthalpy of formation of products - sum of enthalpy of formation of reactants .

As enthalpy of reaction is negative, it means the enthalpy of products is less than the enthalpy of reactants  so answer is :

In an exothermic reaction the energy of the product is less than the energy of the reactants.

7 0
2 years ago
Read 2 more answers
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