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3 years ago

If the dosage for a medication is 225mg/lb, how many grams should a 25-lb child be given?

Chemistry

1 answer:

Oksanka [162]3 years ago

3 0

Answer:

5.625 grams

Explanation:

Start your equation with what you have been given. Place the units you need in your answer on the right side of the equal sign.

225mg

----------- X ----------- X ------------- = ? g

Now start to fill in your equation and use a conversions to get rid of the units you don't want. Convert mg into grams first. The child's weight (25 lb) is placed over 1 just to get the equation lined up properly so you can see how the units cancel out.

225 mg 1 g 25 lb 5.625 g

--------------- X --------------- X ------------- = ---------------

lb 1000 mg 1 1

The lb on the top and bottom cancel each other out and you are left with just grams. Even though it is over one, that is the same at just 5.625 grams.

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Zina [86]

Answer:

Explanation:

n CaCO3 = mass / m.wt

= 500 /( 40 + 12 + 16x 3)

= 5 mole

n CaO = 5 moles ( from the balanced equation we have 1:1 moles )

mass of CaO = nCaO X m.wt

5 x( 40 +16 )

= 280 grams

5 0

3 years ago

What bonds are broken and octane combustion?

dedylja [7]

Answer:

Common combustion reactions break the bonds of hydrocarbon molecules,

Explanation:

the resulting water and carbon dioxide bonds always release more energy than was used to break the original hydrocarbon bonds. That's why burning materials mainly made up of hydrocarbons produces energy and is exothermic.

7 0

2 years ago

Chalcopyrite is an ore with the composition cufes2. what is the percentage of iron in a 39.6 g sample of this ore? answer in uni

iren2701 [21]

<span>Well it depends on percentage by what, but I'll just assume that it's percentage by mass. For this, we look at the atomic masses of the elements present in the compound. Cu has an atomic mass of 63.546 amu Fe has 55.845 amu and S has 36.065 amu Since there are 2 molecules of Sulfur for each one of Cu and Fe, we'll multiply the Sulfur atomic weight by 2 to obtain 72.13 amu So we have not established the mass of the compound in amus 63.546 + 55.845 + 72.13 = 191.521 That is the atomic mass of Chalcopyrite. and Iron's atomic mass is 55.845 So to get the percentage, or fraction of iron, we take 55.845 / 191.521 Which comes out to 29.15% by mass Mass of the sample is not needed for this calculation, but since the question mentions it I would go ahead and check if the question isn't also asking for the mass of Iron in the sample as well, in which case you just find the 29.15% of 67.7g</span>

5 0

3 years ago

Consider the following reaction between calcium oxide and carbon dioxide: CaO(s)+CO2(g)→CaCO3(s) A chemist allows 14.4 g of CaO

sweet-ann [11.9K]

Answer:

Theoretical yield =26.03 g

Percent yield = 87%

Limiting reactant = CaO

Explanation:

Given data:

Mass of CaO = 14.4 g

Mass of CO₂ = 13.8 g

Actual yield of CaCO₃ = 22.6 g

Theoretical yield = ?

Percent yield = ?

Limiting reactant = ?

Solution:

Chemical equation:

CaO + CO₂ → CaCO₃

Number of moles of CaO:

Number of moles = Mass /molar mass

Number of moles = 14.4 g / 56.1 g/mol

Number of moles = 0.26 mol

Number of moles of CO₂:

Number of moles = Mass /molar mass

Number of moles = 13.8 g / 44 g/mol

Number of moles = 0.31 mol

Now we will compare the moles of CO₂ and CaO with CaCO₃ .

CO₂ : CaCO₃

1 : 1

0.31 : 0.31

CaO : CaCO₃

1 : 1

0.26 : 0.26

The number of moles of CaCO₃ produced by CaO are less it will be limiting reactant.

Mass of CaCO₃: Theoretical yield

Mass of CaCO₃ = moles × molar mass

Mass of CaCO₃ =0.26 mol × 100.1 g/mol

Mass of CaCO₃ = 26.03 g

Percent yield:

Percent yield = actual yield / theoretical yield × 100

Percent yield = 22.6 g/ 26.03 g × 100

Percent yield = 0.87× 100

Percent yield = 87%

Limiting reactant:

The number of moles of CaCO₃ produced by CaO are less it will be limiting reactant.

7 0

3 years ago

Most oxygen in our atmosphere _____. has two oxygen atoms has three oxygen atoms combines with carbon has a single oxygen atom

Morgarella [4.7K]

Answer:

has Two oxygen atoms

Explanation:

Oxygen is a diatomic element hence exists as O2 for majority of its existence in our atmosphere. Although small portion does exist in form of O3 which protects earth from sun's harmful ray, the majority portion of oxygen has O2 which is the oxygen we breathe.

8 0

3 years ago