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klasskru [66]
3 years ago
14

Select the correct answer. What is the SI unit of time?

Chemistry
2 answers:
photoshop1234 [79]3 years ago
7 0

Option A: second

SI units are international system of units. This is defined as a system of units of physical quantities such as mass, length, temperature, current etc. Some of the physical units are gram, meter, second etc. along with the set of prefixes which indicates the multiplication and division with some power of 10.

For same physical quantities, these units are inter convertible For example,

1 g=10^{-3}kg

and,

1 g=10^{3}mg

Here, g (gram), kg (kilogram) and mg (milligram) all are units of mass.

The units of time are second, minute, hour, day and year. Here, second is the SI unit and all the units are inter convertible as  follows:

1 year=365 days

1 day=24 hours

1 hour=60 minutes

1 minute-60 seconds

Thus, the SI unit of time is second.


Leni [432]3 years ago
5 0

Answer:

A. second

Explanation:

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In 1909 Fritz Haber discovered the workable conditions under which nitrogen, N2(g), and hydrogen, H2(g), would combine using to
labwork [276]

Answer : 51.8 g of nitrogen are needed to produce 100 grams of ammonia gas.

Solution : Given,

Mass of NH_3 = 100 g

Molar mass of NH_3 = 27 g/mole

Molar mass of N_2 = 28 g/mole

First we have to calculate moles of NH_3.

\text{ Moles of }NH_3=\frac{\text{ Mass of }NH_3}{\text{ Molar mass of }NH_3}= \frac{100g}{27g/mole}=3.7moles

The given balanced chemical reaction is,

N_2(g)+3H_2(g)\rightarrow 2NH_3(g)

From the given reaction, we conclude that

2 moles of NH_3 produced from 1 mole of N_2

3.7 moles of NH_3 produced from \frac{1mole}{2mole}\times 3.7mole=1.85moles of N_2

Now we have to calculate the mass of N_2.

Mass of N_2 = Moles of N_2 × Molar mass of N_2

Mass of N_2 = 1.85 mole × 28 g/mole = 51.8 g

Therefore, 51.8 g of nitrogen are needed to produce 100 grams of ammonia gas.

5 0
2 years ago
Given the balanced equation representing a reaction: 2na(s) + cl2(g) → 2nacl(s) + energy if 46 grams of na and 71 grams of cl2 r
igor_vitrenko [27]
Answer is: 2) 117g.
2Na + Cl₂ → 2NaCl
Step 1: calculate amount of substance of sodium and chlorine.
n(Na) = m(Na)÷M(Na) = 46g ÷ 23 g/mol = 2 mol.
n(Cl₂) = m(Cl₂)÷M(Cl₂) = 71g ÷ 71 g/mol = 1 mol.
Step 2: calculate amount of substance and mass of sodium-chloride.
Because both sodium and chlorine react completely, we can use both n to compare with n of NaCl.
n(Na) : n(NaCl) = 2:2, 2 mol : n(NaCl) = 2:2
n(NaCl) = 2mol, m(NaCl) = 2mol ·5805 g/mol = 117 g.

6 0
3 years ago
El fluoruro de hidrógeno HF que se utiliza en
Blizzard [7]

Answer:

25.6g de HF son producidos

Explanation:

<em>...¿Cuánto HF es producido?</em>

Para resolver este problema debemos convertir la masa de cada reactivo a moles usando su masa molar. Como la reacción es 1:1, el reactivo con menor número de moles es el reactivo limitante. Con las moles del reactivo limitante podemos obtener las moles de HF y su masa así:

<em>Moles CaF2:</em>

Masa molar:

1Ca = 40g/mol

2F = 19*2 = 38g/mol

40+38 = 78g/mol

50g CaF2 * (1mol/78g) = 0.641 moles CaF2

<em>Moles H2SO4:</em>

Masa molar:

2H = 2g/mol

1S = 32g/mol

4O = 64g/mol

98g/mol

100g H2SO4 * (1mol / 98g) = 1.02 moles H2SO4

Como las moles de CaF2 < Moles H2SO4: CaF2 es reactivo limitante.

<em>Moles HF usando la reacción:</em>

0.641 moles CaF2 * (2mol HF / 1mol CaF2) = 1.282 moles HF

<em>Masa HF:</em>

Masa molar:

1g/mol + 19g/mol = 20g/mol

1.282 moles HF * (20g/mol) =

<h3>25.6g de HF son producidos</h3>
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