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Pavel [41]
2 years ago
5

Question 21 of 25 Which of the following requires a chemical change?

Chemistry
2 answers:
Vesna [10]2 years ago
3 0

Answer:

c . Letting the fizz escape from a soda

lilavasa [31]2 years ago
3 0
Answer: a

because there is a fire, it is a chemical change causing the marshmallow to melt.
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Will mark brainliest!
777dan777 [17]
People use data tables and graphs in many financial careers and when looking at the statistics for something as simple as what they saw on the news, etc. When scientists use them, they’re both using them to see the numbers and the facts. They’re both able to use graphs and data tables to help them. They are different though because scientists use them for science related things like how much a tree grew in a year while everyday people use them to see the average amount of drop outs per year or something along those lines.

Data tables and graphs are very vital to a scientists job. They help them easily collect and organize information to where anyone can read it. It may not be absolutely necessary, but it’s something every scientist uses.

Any scientist doing any sort of research would use them. Whether they’re a biologist, geologist or whatever, they all use graphs and data tables to help them organize their research.
4 0
2 years ago
If 88.0 L of natural gas, which is essentially methane (CH4), undergoes complete combustion at 720. mm Hg and 22ºC, how many gra
mr_godi [17]

126 grams of H2O is formed.

Explanation:

Data given:

volume of the gas = 88 Liters

pressure = 720 mm Hg or 0.947 atm

temperature T = 22 Degrees or 295.15 K

R = 0.08021 atm L/mole K

n =?

The formula is used is of ideal gas law to know the number of moles of CH4 undergoing combustion.

PV = nRT

n = \frac{PV}{RT}

putting the values in the equation

   = 0.947 X 88/ 0.08021 X 295.15

n = 3.5 moles

balanced reaction for combustion of methane

CH4 + O2  ⇒ CO2 + 2H20

1 mole of CH4 undergoes combustion to form 2 moles of water

3.5 moles will give x moles of water

2/1 = x/3.5

x =  7 moles of water  (atomic mass of water = 18 gram/mole)

mass = atomic mass x number of moles

mass = 18 x 7

          =126 grams of water is formed.

7 0
3 years ago
LiOH+HBr---> LiBr +h20 If you start with 10.0 grams of lithium hydroxide, how many grams of lithium bromide will be produced?
kicyunya [14]
<span>LiOH+HBr---> LiBr +h20. Moles of LiOH = 10/24 = 0.41moles. According to stoichiometry, moles of LiOH = moles of LiBr = 0.41moles. Therefore mass of LiBr =moles of LiBr x molecular weight of LiBr = o.41 x 87 = 35.67g. Hope it helps </span>
7 0
3 years ago
Dilute 0.407M &amp; 2.56L solution to 7.005L. CF?
Alenkinab [10]

Answer:

C₂ = 0.149 M

Explanation:

Given data:

Initial concentration = 0.407 M

Initial volume = 2.56 L

Final volume = 7.005 L

Final concentration = ?

Solution:

Formula:

C₁V₁ = C₂V₂

C₁ = Initial concentration

V₁ = Initial volume

C₂ = Final concentration

V₂ =Final volume

Now we will put the values.

0.407 M × 2.56 L =  C₂ × 7.005 L

1.042 =  C₂ × 7.005 L

C₂ = 1.042 M.L / 7.005 L

C₂ = 0.149 M

5 0
3 years ago
If 24.6 grams of lithium react with excess water, how many liters of hydrogen gas can be produced at 301 Kelvin and 1.01 atmosph
andreev551 [17]
Answer: 43.3 l


Explanation:

1) Chemical equation:
2 Li(s) + 2 H₂O (l) → 2LiOH(aq) + H₂ (g)

2) Mole ratios:

2 mol Li : 2 mol H₂O : 2 mol LiOH : 1 mol H₂

3) Number of moles of Li that react

n = mass in grams / atomic mass = 24.6g / 6.941 g/mol = 3.54 moles

4) Yield

Proportion:

2 mol Li / 1 mol H₂ = 3.54 mol  Li/ x


⇒ x = 3.54 mol Li × 1 mol H / 2 mol Li = 1.77 mol H₂

4) Ideal gas equation

PV = nRT ⇒ V = nRT / P

V = 1.77 mol × 0.0821 [atm×l / (mol×K)] × 301 K / 1.01 atm = 43.3 l


V = 43.3 l ← answer



7 0
3 years ago
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