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3 years ago

All molecules are always made of

Chemistry

2 answers:

Mademuasel [1]3 years ago

6 0

Atoms that are held together by chemical bonds

Andreas93 [3]3 years ago

5 0

Answer:

Atoms and matter

Explanation:

atoms are the building blocks and matter is everything

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1. Phosphorous reacts with bromine to form phosphorous tribromide. If 35.0 grams of bromine

Anastaziya [24]

Answer:

70.6 %

Explanation:

First step, we define the reaction:

2P + 3Br₂ → 2PBr₃

We determine the moles of reactant:

35 g . 1mol / 159.8 g = 0.219 moles

We assume, the P is in excess, so the bromine is the limiting reagent.

3 moles of Br₂ can produce 2 moles of phophorous tribromide

Then, 0.219 moles may produce (0.219 . 2) /3 = 0.146 moles of PBr₃

We convert moles to mass:

0.146 mol . 270.67 g /mol = 39.5 g

That's the 100 % yield reaction, also called theoretical yield. The way to determine the % yield is:

(Yield produced / Thoeretical yield) . 100

(27.9 / 39.5) . 100 = 70.6 %

7 0

3 years ago

A sample of a compound containing boron (B) and hydrogen (H) contains 5.443 g of B and 1.522 g of H. The molar mass of the compo

Svetach [21]

You are calculating the empirical formula of this chemical compound, which is the question with moles, molar mass, and number of moles.

first you divide the mass of BORON by its molar mass(relative formula mass)because there is a formula about moles state: number of moles=mass/molar mass.

So, 5.443/11 is about 0.5. Then, the RFM of H is 1, so the number of mole is 1.522/1=1.522.

Next, you get the number of moles in order is; 0.5 and 1.522. Now we need to look at the ratio between these numbers. 0.5 is smaller so we use it as the ratio of 1. next use 1.522/0.5 is 3.044 which has a greatest common factor of 3. so the empirical formula is BH3.

Now we are going to solve the molecular formula.

the molar mass ofthis compound is 30g, so we're going to find the RFM of the empirical formulsof BH3 first.

11+3=14.

now we see how many times 14 goes into 30. 30/14=2.14 which is about 2.

So now we need to times the subscript of the empirical formula by two.

thus, the molecular formula is B2H6.

To solve this kind of questions, there are many steps:Know what you are calculating about, it's about the molecular formula, so you need to find out the number of moles of each elements. then use the molar mass of the whole compound to calculate the molecular formula.

1) Find the RFM of the element, because that is the molar mass(mass of 1 mole) of this element.

2) number of moles= mass/molar mass. use this formula to help you get the number of moles of each element in this compound

3) look at the relationship between the number of moles of each elements. find out the ratio between them.

4) then use the molarmass of the whole compound to find the molecular formula. molar mass of the whole compound/RFM(molar mass) of the empirical formula of elements= the number you need to multiply by the subscript of the empirical formula to get the molecular formula.

please tell me if i got anything wrong;)

4 0

2 years ago

Convert 8.876 × 10^12 m^2 to units of km^2.

Darya [45]

Answer:

$8.876\times 10^{18}\ km^2$

Explanation:

In this problem, we need to convert $8.876 \times 10^{12}\ m^2$ to km².

We know that,

1 km = 1000 m

⇒ 1 km² = 10⁶ m²

So,

$8.876 \times 10^{12}\ m^2=8.876 \times 10^{12}\times 10^6\ km^2\\\\=8.876\times 10^{18}\ km^2$

So, $8.876 \times 10^{12}\ m^2$ is equal to $8.876\times 10^{18}\ km^2$ .

7 0

3 years ago

Which materials typically make up the a horizon in soil?

saw5 [17]

The A horizon is a surface horizon that largely consists of minerals (sand, silt, and clay) and with appreciable amounts of organic matter. This horizon is predominantly the surface layer of many soils in grasslands and agricultural lands.These materials typically accumulate through a process termed illuviation, wherein the materials gradually wash in from the overlying.

7 0

3 years ago

If approximately equal volumes of an acid and a base of equal strengths are combined, the resulting solution should have a pH of

Masja [62]

Answer : The resulting solution will have a pH of 7.

Explanation:

Whenever acid and base reacts with each other to form water molecule is called Neutralization reaction. This water molecules is formed from the hydronium ion ( $H^+$ ) from acid and hydroxide ion( $OH^-$ ) from base.

When the equal volumes of acid and base of equal strength are combined, the resulting pH of the solution becomes 7.

The pH 7 value means that the solution is neutral.

4 0

3 years ago

Read 2 more answers