Getting Error while doing automation using selenium

when I execute full script when child window opens its automatically execute next line of script i.e., "ac = web.find_element('xpath','//[id="ton"]')". How to wait for captcha input then after input when I chick on submit button it will execute next line of script.

from selenium import webdriver
from tkinter import *
from PIL import Image, ImageTk

root = Tk()
root.geometry("200x200")

def kcauto():

    web = webdriver.Chrome()
    global myimg

    def capp():
        ca = web.find_element('xpath', '/[id="captcha"]')
        ca.send_keys(cvalue.get())

    top = Toplevel()
    top.title('second')
    myimg = ImageTk.PhotoImage(Image.open('captcha.png'))
    mylab = Label(top, image=myimg)
    mylab.pack(pady=20)
    myentry = Label(top)
    myentry.pack()
    cvalue = StringVar()
    Centry = Entry(top, textvariable=cvalue)
    Centry.pack(pady=20)
    mybutton = Button(top, text='Submit', command=capp)
    mybutton.pack()

    ano = '031191'
    ac = web.find_element('xpath','//[id="ton"]')
    ac.send_keys(ano)

    
b2 = Button(root, fg="black", text="Single", padx=30, pady=20, command=kcauto)
b2.grid(row=2, column=2)

root.mainloop()

Getting Error:

Exception in Tkinter callback
Traceback (most recent call last):
    File "D:\ct\Python\Python310\lib\tkinter\__init__.py", line 1921, in __call__
    return self.func(*args)
    File "D:\ct\PycharmProjects\auto\ir.py", line 52, in kcauto
    ac = web.find_element('xpath','//[id="ton"]')