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3 years ago

HeLpPp asap I’ll mark you as brainlister

Chemistry

1 answer:

jeka57 [31]3 years ago

8 0

It’s 1 or 3 sorry if this is wrong

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2. How many calories are needed to raise 50 g of iron from 55°C to 200°C? (c = 0.110 cal/g °C)

lord [1]

Answer:

Q = 797.5 cal

Explanation:

Given that,

Mass of iron, m = 50 g

The temperature rises from 55°C to 200°C.

We need to find the heat needed to raise the temperature. The heat raised is given by :

$Q=mc\Delta T$

Put all the values,

$Q=50\times 0.11\times (200-55)\\\\Q=797.5\ cal$

So, 797.5 calories of heat is needed.

3 0

3 years ago

The data table shows the rate of the decomposition reaction of hydrogen

const2013 [10]

Answer:

b. the reaction slows down over time as the reactants get used up

Explanation:

just took the test, i hope this helps!!

make sure to take care of yourself :]

7 0

3 years ago

Read 2 more answers

a radioisotope has a half life of three hours how much of a 120g sample remains after 9 hours. what will the g amount be after 3

aksik [14]

$\huge\boxed{♔︎Answer♔︎}$

60g after 3 hours, 30g after 6 hours and 15g after 9 hours

Explanation:

Weight of the radioactive sample = 120g

half life time period = 3 hours

(a) The weight of sample after 3 hours

$\textsf{ No. of half lives} = \sf \cancel\frac{3}{3} = 1$

The fraction of sample left

$\sf { \frac{1}{2} }^{1} = \frac{1}{2}$

Mass of the sample left

$\sf \frac{1}{2} \times 120 = \cancel\frac{120}{2} = 60g$

60g of sample is left after 3 hours

(b) The weight of sample after 6 hours

$\textsf{ No. of half lives} = \sf \cancel\frac{6}{3} = 2$

The fraction of the sample left

$\sf { \frac{1}{2} }^{2} = \frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$

Mass of the sample left

$\sf \frac{1}{4} \times 120 = \cancel\frac{120}{4} = 30g$

30g of sample is left after 6 hours

$\textsf {No. of half lives} = \sf \cancel\frac{9}{3} = 3$

The fraction of sample left

$\sf { \frac{1}{2} }^{3} = \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = \frac{1}{8}$

Mass of sample left

$\sf \frac{1}{8} \times 120 = \cancel \frac{120}{8} = 15g$

15g of sample is left after 9 hours.

3 0

2 years ago

139%

GaryK [48]

Answer:

The percent composition of this compound is 94%

Explanation:

The reaction can be formed as

$2 \mathrm{Fe}+3 \mathrm{Cl}_{2} \rightarrow 2 \mathrm{FeCl}_{3}$

$\frac{\text { Weight of } \mathrm{Cl}_{2}}{\text { 3* Molar Mass of } \mathrm{Cl}_{2}}=\frac{\text { Weight of } \mathrm{Fe}}{2 * \text { Molar Mass of Fe }}$

$\frac{\text { Weight of } \mathrm{Cl}_{2}}{3 *(2 * 35.5)}=\frac{3.56}{2 * 55.8}$

$\text { Weight of } C l_{2}=\frac{3.56 * 3 * 71}{2 * 55.8}=6.79 \mathrm{g}$

$\mathrm{n}\left(\mathrm{Cl}_{2}\right)=\mathrm{m}\left(\mathrm{Cl}_{2}\right) / \mathrm{M}\left(\mathrm{Cl}_{2}\right)=6.79 / 71=0.1 \mathrm{m}$

$\mathrm{n}(\mathrm{Fe})=\mathrm{m}(\mathrm{Fe}) / \mathrm{M}(\mathrm{Fe})=3.56 / 55.8=0.06 \mathrm{m}$

Based on no. of iron reacted,

$\mathrm{n}(\text { moles of } \mathrm{Fe})=\mathrm{n}\left(\text { moles of } \mathrm{FeCl}_{3}\right)$

n = m/M

$\mathrm{m}\left(\mathrm{FeCl}_{3}\right)=\mathrm{n}^{*} \mathrm{M}=0.06^{*} 162.5=9.75 \mathrm{g}$

% composition of $FeCl_3$

= $(9.75 / 10.39)^{*} 100$

= 94%

6 0

3 years ago

Describe one possible economic impact of redox reactions. How might that impact be diminished?

Alex777 [14]

Redox reaction has a great economic impact. many product that we use in our daily lives are made using redox reaction. some of which are electroplating, that we use in our watches. and redox reaction also caused the rusting of irons, so buildings will rust and become brittle

4 0

4 years ago